LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 


Class 


ft 


FIG.    1.  —  CONVEYING  TAN-BARK.  —  ENGLISH  MANUFACTURE 
OF  WHITE  LEAD. 


THE   LEAD  AND  ZINC 
PIGMENTS 


BY 
CLIFFORD    DYER    HOLLEY,    M.S.,   PH.D. 

CHIEF    CHEMIST    ACME    WHITE    LEAD    AND    COLOR    WORKS 


FIRST  EDITION 

FIRST    THOUSAND 


OF    THE 

UNIVERSITY 

Of 


NEW   YORK 

JOHN    WILEY    &   SONS 

LONDON:    CHAPMAN   &   HALL,  LIMITED 

1909 


•r\^ 


COPYRIGHT,  1909, 

BY 
CLIFFORD   DYER    HOLLEY 

(Entered  at  Stationers'  Hall) 


Stanhope  ipress 

F.H.   GILSON     COMPANY 
BOSTON.     U.S.A 


INTRODUCTION. 


POSSIBLY  in  no  other  country  has  the  art  of  pigment  and 
paint  making  reached  as  high  a  level  as  in  the  United  States. 
Certainly  in  no  other  country  has  the  paint  industry 
developed  as  rapidly  during  the  last  forty  years  as  it  has 
in  America.  The  making  of  one  hundred  and  fifty  thousand 
tons  of  lead  pigments  and  over  seventy  thousand  tons  of 
zinc  pigments,  resulting  in  the  manufacture  of  over  one 
hundred  million  gallons  of  paint  besides  the  enormous 
sales  of  lead  in  oil,  constitutes  an  industry  that  is  to  be 
counted  among  the  important  industries  of  the  country. 
And  yet  until  the  passage  of  the  first  efficient  and  vigor- 
ous paint  law  in  1905,  enacted  by  the  state  of  North 
Dakota,  and  the  court  proceedings  attendant  thereto  for 
the  determining  of  the  constitutionality  of  that  law,  those 
interested  in  the  subject  of  pigments  and  paints  were  com- 
pelled to  turn  to  English  books  for  information,  as  our  own 
literature  was  noticeable  only  for  its  meagerness. 

New  pigments  have  come  into  use  during  the  last  ten 
years,  new  processes  have  been  developed  for  the  manu- 
facture of  the  older  pigments,  new  combinations  of  pig- 
ments have  been  worked  out  that  have  secured  results 
hitherto  unattainable.  Yet  up  to  the  time  mentioned 
above,  except  for  short  articles  in  some  of  the  trade  papers, 
these  improvements  and  innovations  remained  practically 
unnoticed.  Since  public  attention  has  been  directed  to 
the  paint  industry  by  the  enactment  of  the  various  state 
laws  regarding  the  sale  of  paint  materials,  several  excellent 


20547;! 


yi  INTRODUCTION. 

American  works  have  been  written  on  this  subject,  but 
the  majority  of  them  have  been  directed  more  particularly 
toward  the  compiling  of  analytical  methods  and  data  than 
to  the  manufacture  and  uses  of  the  various  pigments. 

In  this  work  the  author  has  attempted  to  record  the 
progress  made  in  the  United  States  in  the  manufacture 
of  the  more  important  pigments,  and  hence  but  little  space 
has  been  given  to  European  methods  and  processes  except 
for  comparison,  as  they  have  been  discussed  in  detail  in 
various  English  and  European  works. 

The  writer  wishes  to  express  his  appreciation  for  the 
valuable  information  and  data  furnished  him  by  Mr. 
Willson  H.  Rowley,  who  for  many  years  has  been  promi- 
nently identified  with  the  white  lead  industry  and  who 
has  done  much  to  place  it  on  a  more  sanitary,  scientific, 
and  economical  basis. 

DETROIT,  MICH.,  July  1,  1908. 


CONTENTS. 


CHAPTER   I. 

PAGE 

WHITE  LEAD  IN  ANCIENT  TIMES 1 

1.  Importance  of  white  lead  industry;  2.  Composition; 
3.  Historical;  6.  Essential  conditions  for  manufacture  of 
white  lead;  10.  Early  improvements;  11.  Effect  of  the 
revival  of  learning;  13.  Development  of  the  lead  industry 
by  the  Dutch;  14.  Early  adulteration  of  white  lead; 
16.  Manufacture  of  white  lead  in  seventeenth  century; 
18.  The  Dutch  method  of  manufacture;  20.  English 
method  of  manufacture. 


CHAPTER   II. 

DEVELOPMENT  OF  THE  WHITE  LEAD  INDUSTRY  IN  THE  UNITED 

STATES 14 

21.  Early  use  of  white  lead;  23.  First  white  lead  plant; 
25.  Effect  of  War  of  1812;  26.  Other  early  manufacturers; 
27.  Adoption  of  uniform  scale  of  prices;  29.  Formation 
of  new  companies;  30.  Effect  of  the  Civil  War;  31.  Patents 
issued;  33.  Improvements. 


CHAPTER   III. 

DEVELOPMENT  OF  THE  WHITE  LEAD  INDUSTRY  IN  THE  UNITED 

STATES  (Continued) 23 

34.  Formation  of  National  Lead  Trust;  35.  Absorption  of 
other  companies;  36.  Dissolution  of  National  Lead  Trust; 
37.  Formation  of  National  Lead  Company;  39.  Different 
branches  of  National  Lead  Company;  40.  Operation  of 
factories;  41.  Independent  companies;  42.  The  Bailey 
process;  44.  The  United  Lead  Company;  46.  Growth  of 
United  Lead  Company;  47.  Acquisition  of  the  United  Lead 
Company:  48.  Number  and  location  of  lead  plants  in  the 
United  States. 

vU 


Vill  CONTENTS. 

CHAPTER   IV. 

PAGE 

BRANDS,  PRODUCTION  AND  PRICES  OF  WHITE  LEAD 34 

49.  Brands;  50.  Short  weight  packages;  51.  Annual  pro- 
duction of  white  lead;  52.  Sale  of  dry  white  lead;  53.  Dif- 
ferential between  pig  lead  and  white  lead. 

CHAPTER  V. 

THE    MODERN   APPLICATION   OF   THE   DUTCH   PROCESS   IN   THE 

UNITED  STATES 42 

54.  Present  importance  of  the  Dutch  Process;  55.  Processes 
in  use;  56.  Grade  of  pig  lead  required;  57.  Casting  the 
buckles;  58.  Building  the  stack;  59.  Reactions  involved 
in  the  process;  61.  Conditions  required  for  successful 
corrosion;  62.  Taking  down  the  stack;  64.  Sandy  lead. 

CHAPTER   VI. 

THE   MODERN   APPLICATION   OF   THE   DUTCH   PROCESS   IN   THE 

UNITED  STATES  (Continued) 56 

66.  Disintegrating  the  buckles;  67.  Washing  the  lead; 
68.  Importance  of  thorough  washing;  69.  Drying  the 
lead;  71.  Loss  of  lead  in  washing;  72.  Effect  of  sandy 
lead  in  paints;  73.  Cost  of  a  stack  operation;  75.  Econ- 
omy of  process;  76.  Variation  in  quality;  77.  Lack  of 
proper  grinding  of  white  lead;  78.  Changes  that  may  take 
place  in  grinding;  79.  English  methods  of  grinding; 
80.  Combination  leads;  82.  Pulp  ground  lead;  83.  Char- 
acteristics of  pulp  lead. 


CHAPTER   VII. 

THE  CARTER   PROCESS 74 

85.  History;  86.  Adams  White  Lead  Company;  87.  Omaha 
White  Lead  Company;  88.  Formation  of  the  Carter  Com- 
pany; 90.  Underlying  principles;  91.  Granulating  the 
lead:  92.  Corrosion;  94.  Washing  and  floating;  95.  Chem- 
ical composition;  96.  Characteristics;  97.  Success. 


CONTENTS.  IX 

CHAPTER  VIII. 

PAGE 

THE  MILD  PROCESS  (Rowley) 85 

98.  Derivation  of  name;  100.  Early  attempts;  101.  Solu- 
tion by  W.  H.  Rowley;  102.  Early  training;  103.  Atom- 
ization  with  superheated  steam;  104.  Growth  of  process; 
105.  Simplicity  of  process;  106.  Atomizing  the  lead; 
107.  Oxidizing  and  hydrating;  109.  Carbonating; 
110.  Control;  111.  Advantages  of  process;  112.  Not  a 
precipitation  process. 

CHAPTER   IX. 

MATHESON  PROCESS 101 

114.  Nature  of  process;  115.  Development  in  the  United 
States;  116.  Characteristics  of  Matheson  lead;  117.  Manu- 
facture; 119.  Uses. 

CHAPTER  X. 

THE  SUBLIMED  LEAD  PIGMENTS 108 

120.  Sublimed  white  lead;  121.  Early  developments; 
123.  Sublimation  of  the  ore;  124.  Condensation  of  the 
fume;  125.  Bag-room;  126.  Uniformity  of  product; 
127.  Chemical  constitution;  128.  Yearly  production; 
129.  Physical  characteristics;  131.  Uses  of  sublimed  white 
lead;  132.  Chalking;  133.  Comparative  whiteness;  134. 
Inertness  toward  tinting  colors;  135.  Sublimed  blue  lead; 
136.  Properties;  137.  Composition;  138.  Sublimed  lead 
oxide. 

CHAPTER   XI. 

WHITE  LEAD  MANUFACTURE  IN  EUROPE 122 

139.  Comparative  Costs  of  manufacture,  English  regulations'; 
142.  English  methods;  143.  Characteristics  of  English 
white  lead;  144.  German  chamber  process;  145.  Klagen- 
furth  modification;  147.  Present  German  methods; 
149.  Effecting  the  corrosion;  151.  Rapidity  of  corrosion; 
153.  Lack  of  success  in  the  United  States;  157.  Present 
French  practice. 


X  CONTENTS. 

CHAPTER  XII. 

PAGE 

PROPERTIES  OF  WHITE  LEAD 133 

158.  Composition;  160.  The  higher  carbonates;  161.  Ageing 
of  white  lead;  163.  Free  fatty  acids;  164.  Fineness  of 
particles;  165.  Action  of  white  lead  on  linseed  oil;  167. 
Stability  of  white  lead  toward  heat;  169.  Reactions  with 
acids;  170.  Solubility;  171.  Action  of  sulphur  compounds; 
172.  Chalking  of  white  lead;  ,173.  Effect  of  residual  ace- 
tates; 174.  Protracted  oxidation;  175.  White  lead  specifi- 
cations. 


CHAPTER   XIII. 

LEAD  POISONING 143 

179.  The  English  White  Lead  Commission;  180.  Lead 
poisoning  in  the  United  States;  182.  English  regulations; 
183.  Duties  of  occupiers;  184.  Duties  of  persons  employed ; 
185.  English  Statistics;  186.  Precautions  adopted  by  the 
French;  188.  Recent  improvements;  190.  Restrictive 
legislation;  191.  Danger  to  women;  192.  Symptoms  of 
lead  poisoning;  194.  Effect  on  the  nervous  system;  195. 
Chronic  lead  poisoning;  196.  Absorption  through  the 
skin. 


CHAPTER  XIV. 

MANUFACTURE  OF  ZINC  OXIDE 152 

197.  Ancient  history;  198.  Production  on  a  commercial 
scale;  199.  Work  of  LeClaire;  200.  LeClaire's  Process; 
201.  Present  French  process;  202.  Composition;  204. 
Processes  in  use  in  the  United  States;  205.  Work  of  Jones 
and  Wetherill;  206.  Zinc  oxide  plants  in  United  States; 
207.  Development  of  the  New  Jersey  zinc  mines;  209. 
Controversey  regarding  the  ownership  of  the  deposits; 
210.  Composition  of  Franklinite  ore;  213.  Chemical  com- 
position; 214.  Preliminary  treatment  of  the  ore;  216.  The 
oxide  furnaces;  218.  Collection  of  the  fume;  219.  Palmer- 
ton  plant ;  220.  Purity  of  New  Jersey  zinc  oxide ;  222.  Fur- 
nace assays;  224.  Spiegeleisen;  225.  The  Mineral  Point 
works. 


CONTENTS.  Xl 

CHAPTER   XV. 

PAGE 

PROPERTIES  AND  USES  OF  ZINC  OXIDE 175 

226.  Properties;  227.  Solubility;  228.  Composition  of  com- 
mercial grades;  229.  Analyses  of  zinc  oxide  made  from  the 
ore;  230.  Analyses  of  zinc  oxide  made  from  spelter; 
231.  Analyses  of  mineral  point  zinc  oxides;  232.  Analyses 
of  zinc  oxide  — Scott;  234.  Sulphur  dioxide  and  zinc  sul- 
phate; 235.  Imported  zinc  oxides;  236.  Comparative 
prices;  237.  Lack  of  affinity  for  moisture;  238.  Zinc  oxide 
as  a  paint  pigment;  241.  Production  and  value  of  zinc 
oxide. 

CHAPTER   XVI. 

MANUFACTURE  OF  LEADED  ZINC 182 

242.  History;  243.  Comparison  with  Eastern  methods; 
244.  Process  of  manufacture;  246.  Characteristics;  248. 
Zinc  sulphate;  249.  Result  on  the  life  of  the  paint. 


CHAPTER   XVII. 

ZINC-LEAD  WHITE 188 

250.  Source;  252.  Early  manufacture;  253.  Absorption  by 
United  States  Smelting  Company;  254.  Standard  of  com- 
position; 255.  Sublimation  of  fume;  256.  Collection  of 
fume;  257.  Final  treatment;  258.  Production;  259.  Phys- 
ical properties;  260.  Recent  improvements;  261.  Use  in 
house  paints;  262.  Use  in  the  manufacturing  trades; 
264.  Chemical  composition;  265.  Zinc  sulphate;  266. 
Washing. 


CHAPTER  XVIII. 

THE  OXIDES  OP  LEAD 200 

267.  Classification;  269.  Lead  suboxide;  270.  Litharge; 
271.  Early  confusion  regarding  nature  of  litharge;  272. 
Development  of  litharge  industry;  273.  Manufacture; 
274.  Cupellation  process;  275.  Other  processes;  276. 
Properties;  278.  Commercial  classification;  280.  Produc- 
tion of  litharge  in  United  States;  281.  Imports, 


Xll  CONTENTS. 

CHAPTER  XIX. 

PAGE 

THE  OXIDES  OF  LEAD  (Continued) 207 

282.  Early  history  of  red  lead;  283.  Early  methods  of 
preparation;  285.  Development  of  the  industry;  287. 
Early  manufacture  in  the  United  States;  288.  Present 
methods  of  manufacture;  289.  Furnace  temperature; 
291.  Dressing;  292.  Coloring;  294.  Modern  improve- 
ments; 295.  The  nitrate  process;  297.  Properties;  298. 
Adulteration;  299.  Selection  for  vermilions;  301.  Orange 
mineral;  302.  Production  and  imports  of  red  lead;  303. 
Production  and  imports  of  orange  mineral. 

CHAPTER   XX. 

THE  LEAD  CHROMATES 217 

304.  Varieties;  305.  Tinting  strength;  306.  Presence  of  lead 
sulphate;  307.  Raw  materials;  308.  Sodium  bichromate; 
309.  Precautions  to  be  observed;  310.  Secret  formulas; 
312.  Practical  formulas;  313.  Precipitation;  314.  Orange 
chrome  yellows;  315.  Addition  of  the  calcium  oxide; 
317.  American  vermilion;  319.  Preparation;  320.  Care 
in  grinding. 

CHAPTER  XXI. 

LlTHOPONE 225 

321.  Early  history;  323.  Zinc  sulphide;  324.  Preparation 
of  zinc  sulphate;  325.  Preparation  of  barium  sulphide; 
327.  Precipitating  and  calcining;  328.  Physical  properties 
of  lithopone;  329.  Reductions;  332.  Comparison  with 
white  lead;  333.  Grades  of  lithopone;  334.  Manufacturers; 
335.  Production. 

CHAPTER  XXII. 

PHYSICAL  PROPERTIES  OF  WHITE  LEAD 230 

336.  Amorphous  character  of  white  lead;  337.  Color;  338. 
Cautions  to  be  observed;  339.  Opacity;  341.  Oil  require- 
ments and  reductions;  343.  Laboratory  tests  for  opacity 
and  covering  power;  344.  Microscopical  measurements; 
345.  Determination  of  specific  gravity;  349.  Displace- 
ment in  oil;  350.  "Bulking"  figure;  351.  The  determina- 
tion. 


CONTENTS.  xiii 

CHAPTER   XXIII. 

PAGE 

PRACTICAL  TESTS 238 

352.   The    North    Dakota    paint    tests;    353.    Reductions; 

354.  Red  Seal,  Eagle,  Carter  and  Sublimed  Lead  white; 

355.  Matheson  White   lead;    356.    Zinc-lead  white;     357. 
Mild    process  white   lead;    358.     New   Jersey  zinc  oxide; 
359.   Covering  tests;  360.    Hard  pine  boards;  361.   Soft 
pine    boards;    362.   Cedar   clapboards;    363.    White    pine 
clapboards;  364.   Conclusion. 

CHAPTER   XXIV. 

THE  ART  OF  GRINDING  WHITE  LEAD,  PASTES  AND  PAINTS 246 

365.  Importance  of  careful  grinding;  366.  Careless  grind- 
ing; 367.  Conditions  to  be  observed;  368.  Mixing  and 
chasing;  369.  Proper  selections  of  stones;  371.  Sources  of 
millstones;  372.  Domestic  stones;  373.  Stone  dressing; 
375.  Types  of  mills;  376.  Best  method  of  dressing  stones; 
377.  Adjustment  of  grooves;  378.  Grinding  pastes; 
379.  Use  of  mill  picks;  380.  Pneumatic  dressing;  381. 
Frequency  of  dressing;  383.  Types  of  dressing;  384.  Speed 
of  mills. 

CHAPTER  XXV. 

ANALYSIS  OF  COMMERCIALLY  PURE  WHITE  LEADS 258 

385.  Sulphur  dioxide;  387.  Sandy  lead;  388.  Determina- 
tion; 389.  Tan-bark;  391.  Metallic  lead;  392.  Lead  sul- 
phate; 393.  Determination;  394.  Volumetric  estimation 
of  lead,  Method  I;  395.  Potassium  bichromate  solution; 
396.  Silver  nitrate  solution;  397.  Method  II;  399.  Molyb- 
date  solution;  400.  Tannic  acid  solution;  401.  Carbon 
dioxide;  405.  Acetic  acid  in  white  lead;  408.  Determina- 
tion; 410.  Conclusions. 


CHAPTER  XXVI. 

ANALYSIS  OF  THE  ZINC  PIGMENTS 268 

411.  Moisture;  412.  Silica;  414.  Sulphur  dioxide;  415. 
Iodine  solution;  416.  Sodium  thiosulphate;  417.  Starch 
paste;  418.  Standardizing  the  thiosulphate  solution; 
419.  Standard  of  acceptance;  420.  Reaction  with  rosin 


xiv  CONTENTS. 

ANALYSIS  OF  THE  ZINC  PIGMENTS  (Continued)  PAGE 

products;  421.  Zinc  sulphate;  423.  Effect;  424.  Lead; 
425.  Method  I;  426.  Method  II;  427.  Method  III; 
428.  Total  Zinc;  429.  Potassium  ferrocyanide  method; 
430.  Standard  zinc  solution;  431.  Standard  potassium 
ferrocyanide  solution;  432.  Uranium  nitrate  solution; 
433.  Standardizing  the  ferrocyanide  solution;  435.  Titra- 
tion  of  sample;  436.  Precipitation  of  zinc  as  carbonate; 
437.  Precipitation  of  zinc  as  phosphate;  438.  Combined 
sulphuric  acid;  441.  Calculations;  442.  Estimation  of 
arsenic  and  antimony  in  zinc-leads;  447.  Preparation  of 
iodine  solution;  449.  Antimony;  450.  Methods  in  use  at 
Canon  City;  451.  Method  I;  455.  Method  II. 


CHAPTER   XXVII. 

ANALYSIS  OF  WHITE  LEAD  AND  PAINTS  IN  OIL 282 

457.  Securing  a  fair  sample;  458.  Variations  from  formula; 
459.  Chemical  changes  in  grinding;  462.  Obtaining  an 
average  sample;  464.  Inaccurate  methods  of  analysis; 
465.  Extraction  of  the  vehicle;  466.  Removal  of  the 
vehicle  for  examination;  467.  Use  of  centrifuge;  470.  Use 
of  volatile  petroleum  thinners;  472.  Characteristics; 
473.  Reporting  results. 


CHAPTER  XXVIII. 

ESTIMATION  OF  WATER  IN  WHITE  LEADS  AND  PAINTS 290 

474.  Occurrence;  475.  Detection;  476.  Estimation;  479. 
Estimation  of  water  with  amyl  reagent;  480.  Preparation 
of  amyl  reagent;  481.  Determination;  482.  Practical 
example. 

CHAPTER  XXIX. 

QUALITATIVE   ANALYSIS   OF   COMBINATION   WHITE   LEADS   AND 

PASTES 295 

483.  Classification;  484.  Inert  pigments;  485.  Barium 
sulphate;  486.  Blanc  Fixe;  487.  Barium  carbonate;  488. 
Calcium  carbonate;  491.  Calcium  sulphate;  493.  Alumi- 
nium silicate;  494.  Magnesium  silicate;  495.  Silica;  497. 
Carbonates;  498.  Barytes;  499.  Sulphates;  500.  Lead; 
501.  Zinc;  502.  Calcium;  503.  Magnesium. 


CONTENTS.  XV 


CHAPTER   XXX. 

PAGE 

QUANTITATIVE  ANALYSIS  OF  COMBINATION  WHITE    LEADS    AND 

PAINTS 302 

504.  Total  lead;  511.  Zinc  oxide;  512.  Standard  potassium 
ferrocyanide  solution;  513.  Uranium  nitrate  solution; 
514.  Standardizing  the  ferrocyanide  solution;  516.  Titra- 
tion  of  sample;  519.  White  lead;  520.  Insoluble  residue; 
521.  Barium  sulphate;  522.  Silica;  523.  Alumina;  524. 
Calcium  and  magnesium  oxides;  525.  Hydrofluoric  acid 
treatment. 

CHAPTER  XXXI. 

LABORATORY  EQUIPMENT  AND  MANIPULATION 310 

530.  Weight  per  gallon;  531.  Specific  gravities;  532.  Rapid 
extraction  pigment;  533.  Estimation  of  water  in  paints; 
534.  Estimation  of  volatile  oils;  535.  Rapid  drying; 
536.  Filtering  by  suction;  537.  Use  of  Gooch  crucible; 
539.  Bottles  for  Standard  solutions. 


APPENDIX 317 

540.  Atomic  weights;  541.  Formulas  and  molecular  weights; 
542.  Factors  for  gravimetric  analysis;  543.  Specific  grav- 
ities corresponding  to  degrees  Baum£  for  liquids  lighter 
than  water;  544.  Table  for  liquids  heavier  than  water; 
545.  Specific  gravity  and  weights  per  gallon;  546.  Speci- 
fic gravity  of  acetic  acid;  547.  Specific  gravity  of  nitric 
acid;  548.  Specific  gravity  of  hydrochloric  acid;  549.  Sul- 
phuric acid;  550.  Measures,  weights  and  temperatures. 


ILLUSTRATIONS. 


1.  Conveying  Tan-bark  —  English  Manufacture  of  White  Lead . 

2.  Wetherill  White  Lead  Works,  1808 16 

3.  Lead  Buckle 21 

4.  Lead  Fibers  —  Bailey  Process 28 

5.  Hammar  Brothers'  White  Lead  Works 30 

6.  Facsimiles  of  Leading  Brands  of  National  Load  Company.  .  .  36 

7.  Facsimiles  of  Leading  Brands  of  National  Lead  Company.  .  .  37 

8.  Pig  Lead  and  Sections  of  Corroding  Pots  Containing  New  and 

Corroded  Buckles 43 

9.  Buckle  Casting  Machine 45 

10.  Electric  Crane  for  Conveying  Tan-bark 47 

11.  Filling  the  Corroding  Pots  —  National  Lead  Company 48 

12.  A  Layer  of  Corroding  Pots  in  Position  —  Eagle  Company.  . .  50 

13.  Completed  Stack  —  Hammar  Brothers 51 

14.  A  Finished  Corrosion,  Showing  Position  of  Flues  —  National 

Lead  Company 52 

15.  Taking  down  a  Stack  —  Eagle  Company 54 

16.  Crushing  Rolls  —  Hammar  Brothers 55 

17.  Water  Grinding  Mills  —  Hammar  Brothers 57 

18.  Drag  and  Washing  Box 58 

19.  Agitating  and  Washing  Tubs  —  National  Lead  Company ....  59 

20.  Drying  Pans  —  Eagle  Company 61 

21.  Truck  Dryer  —  Philadelphia  Textile  Machine  Company 63 

22.  White  Lead  Mixers  —  Eagle  Company 65 

23.  Oil  Grinding  Mills  —  Eagle  Company 68 

24.  English  Type  of  White  Lead  Mill 70 

25.  Plants  of  Carter  White  Lead  Company 75 

26.  Conveyer  and  Melting  Kettle  —  Carter  Process 77 

27.  Corroding  Cylinder  —  Carter  Process 79 

28.  Corroding  Room  —  Carter  Process 81 

29.  Chaser  and  Mixers  —  Carter  Process       83 

30.  Plant  —  Rowley  Lead  Company 86 

31.  Plant  —  Mild  Process  Lead  Company 88 

32.  Atomizing  Apparatus  —  Mild  Process 90 

33.  Blow  Chamber  —  Mild  Process 92 

xvii 


xviii  ILLUSTRATIONS. 

PAGE 

34.  Oxidizers  —  Mild  Process 94 

35.  Float  System  —  Mild  Process 96 

36.  Carbonators  —  Mild  Process 97 

37.  Battery  of  Drying  Pans  —  Mild  Process 99 

38.  Melting  Room  —  Matheson  Process 102 

39.  Corroding  Tanks  —  Matheson  Process 102 

40.  Washing  Presses  —  Matheson  Process 104 

41.  Settling  Tanks  —  Matheson  Process 104 

42.  Vacuum  Driers  and  Filling  Machine  —  Matheson  Process. .  .  .  106 

43.  Pulp  Mill  —  Matheson  Process 106 

44.  Picher  Sublimed  Lead  Works 109 

45.  Sublimed  Lead  Furnaces Ill 

46.  "  Goose  Necks  "  —  Picher  Lead  Company 112 

47.  Bag- room  —  Picher  Lead  Company 114 

48.  Collecting  Hoppers  —  Picher  Lead  Company 116 

49.  Building  the  Stack  —  English  Method 124 

50.  Taking  down  the  Stack  —  English  Method 126 

51.  Particles  Old  Dutch  Process  Lead 135 

52.  Particles  Mild  Process  Lead 135 

53.  Particles  Precipitated  Lead 137 

54.  Particles  Sublimed  White  Lead 137 

55.  Required  Costume  of  English  White  Lead  Worker 145 

56.  Palmerton  Works  —  New  Jersey  Zinc  Company 157 

57.  Oxide  Furnaces  —  Palmerton  Works 161 

58.  Stock  Trestle  —  Palmerton  Works .  . 163 

59.  Blower  Room  —  Palmerton  Works 165 

60.  Bag- room  Building  —  Palmerton  Works 167 

61.  Bag-room  —Palmerton  Works 169 

62.  Blast  Furnace  for  Spiegeleisen  —  Palmerton  Works 170 

63.  Spelter  Plant  —  Palmerton  Works 172 

64.  Plant  of  Mineral  Point  Zinc  Company 173 

65.  Pipe  Line  —  Coffeyville  Plant 184 

66.  Furnaces  —  Coffeyville  Plant 184 

67.  Zinc  Sulphate  on  Paint  Film 186 

68.  Zinc-Lead  Plant  —  U.  S.  Smelting  Company 190 

69.  Furnace  Room  —  U.  S.  Smelting  Company 192 

70.  Refining  Furnaces  —  U.  S.  Smelting  Company 193 

71.  Bag-room  — U.  S.  Smelting  Company 195 

72.  Barrel  Packer  and  Mixers  —  U.  S.  Smelting  Company 197 

73.  Oxide  Works  —  Matheson  &  Co 201 

74.  Oxide  Furnaces  —  National  Lead  Company 203 

75.  Oxide  Furnaces  —  Eagle 210 

76.  Exposure  Fences,  North  Dakota  (West  Side) 239 

77.  Exposure  Fences,  North  Dakota  (East  Side) 242 


ILLUSTRATIONS.  XIX 


PAGE 


78.  Dressing  for  a  Paint  Mill 252 

79.  Adaption  of  Grinding  Surfaces 252 

80.  Adjustment  of  Furrows 253 

81.  Dressing  for  Heavy  Grinding 254 

82.  Dressing  for  20-inch  Mill 255 

83.  Knorr's  Apparatus 263 

84.  Extraction  Apparatus 285 

85.  Estimation  of  Water 291 


Of    THE 

UNIVERSITY 

Of 


THE    LEAD    AND   ZINC 
PIGMENTS. 


CHAPTER  I. 

WHITE  LEAD  IN  ANCIENT  TIMES. 

1.  Importance  of  White  Lead  Industry.  The  lead  prod- 
ucts industries  are  to  be  reckoned  among  the  most  impor- 
tant industries  of  the  country.     Of  the  331,000  tons  of 
lead  produced  in  1907,  it  is  estimated  that  over  135,000 
tons   were   used  in  the  manufacture  of  white  lead,   red 
lead  and  litharge,  an  amount  equivalent  to  over  40  per  cent 
of  the  entire  lead  consumption.     The  conversion  of  this 
amount    of   metal    into    chemical   products    represents   a 
large  outlay  of  capital  and  the  employment  of  a  large 
number  of  workmen,  in  the  nearly  fifty  plants  producing 
these  pigments  in  the  United  States.     The  production  of 
litharge  and  red  lead  is  small,  however,  as  compared  with 
white  lead,  which  required  during  the  year  referred  to  about 
100,000  tons  of  metallic  lead. 

2.  Composition.    White  lead  is  perhaps  the  best  known 
of   all  the  white  pigments  and  has  been  in  general  use 
from    very    ancient   times.     Chemically   white   lead   is   a 
basic  carbonate  of  lead.     A  large  number  of  analyses  of 
the    best    samples   indicate   a   constitutional    formula   of 
2  PbC03-Pb(OH)2,  in  which   there  are  two  molecules  or 
equivalents  of  lead  carbonate  to  one  of  hydroxide,  the 

l 


2  THE  LEAD  AND   ZINC  PIGMENTS. 

combination  being  represented  by  the  following  structural 
formula  : 

pb(OH 


White  lead  may  be  made  to  vary  a  good  deal  in  com- 
position according  to  the  method  and  conditions  of  making, 
and  many  writers  in  comparing  the  more  modern  pigments, 
such  as  sublimed  white  lead  and  zinc-lead  white,  with 
white  lead  have  commented  much  on  these  variations; 
but  white  lead  as  manufactured  to-day,  whether  by  the 
Old  Dutch  process  or  by  the  quick  processes  that  have 
been  found  by  experience  to  be  economically  successful, 
varies  but  comparatively  little  in  composition  as  regards 
the  ratio  of  carbonate  to  hydroxide. 

3.  Historical.  White  lead  was  known  to  the  ancients 
under  the  Greek  name  of  psmithium  and  the  Roman  name 
of  cerussa.  Perhaps  the  earliest  definite  and  reliable 
account  of  its  manufacture  is  given  in  Theophrastus' 
"  History  of  Stones,"  written  about  300  years  before 
Christ,  in  which  the  author  describes  the  method  of  manu- 
facture substantially  as  follows: 

"  Lead  is  placed  in  earthen  vessels  over  sharp  vinegar, 
and  after  it  has  acquired  some  thickness  of  a  sort  of  rust, 
which  it  commonly  does  in  about  ten  days,  they  open 
the  vessels  and  scrape  it  off,  as  it  were,  in  a  sort  of  foul- 
ness; they  then  place  the  lead  over  vinegar  again,  repeat- 
ing over  and  over  again  the  same  method  of  scraping  it 
till  it  has  wholly  dissolved.  What  has  been  scraped  off 
they  then  beat  to  powder  and  boil  for  a  long  time,  and 
what  at  last  subsides  to  the  bottom  of  the  vessel  is  ceruse.  "  1 
1  Theophrastus,  History  of  Stones,  p.  223. 


WHITE   LEAD   IN   ANCIENT  TIMES.  3 

4.  Vitruvius,  writing  in  the  first  century  before  Christ, 
says:  "  It  will  be  proper  to  explain  in  what  manner  white 
lead  is  made.     The  Rhodians  place  in  the  bottom  of  large 
vessels  a  layer  of  vine  twigs,  over  which  they  pour  vinegar, 
and  on  the  twigs  they  lay  masses  of  lead.     The  vessels 
are  covered  to  prevent  evaporation,  and  when,  after  a  cer- 
tain time,  they  are  opened  the  masses  are  found  changed 
into  white  lead."  l 

5.  Pliny,  the  historian,  living  in  the  first  century  A. D., 
mentions  a  native  ceruse  (cerussite)  found  in  Smyrna  which 
the  ancients  made  use  of  for  painting  their  ships,  but  adds 
that"  all  ceruse  is  prepared  from  lead  and  vinegar/'2  and 
the  most  esteemed,  he  adds,  comes  from  Rhodes. 

These  and  other  descriptions  by  the  ancient  writers 
and  historians  can  only  be  regarded  as  imperfect  and  crude 
statements  of  processes  they  personally  knew  little  or 
nothing  about,  and  it  is  natural  that  their  descriptions 
should  be  lacking  in  many  essential  details.  Their 
methods  if  followed  exactly  as  described  would  produce 
only  lead  actate,  which,  besides  being  very  soluble  in 
water,  possesses  but  little  opacity  or  hiding  power. 

6.  Essential  Conditions  for  Manufacture  of  White  Lead. 
Three  conditions  are  essential  for  the  proper  manufacture 
of  white  lead  from  metallic   lead  and  vinegar  or  acetic 
acid: 

1.  The  placing  of  the  lead  above  the  acid  so  that  it 

would  not  come  in  contact  with  it. 

2.  A  long  continued  gentle  heat,  such  as  would  be 

obtained  by  the  use  of  horse  manure  or  by  the 
fermentation  of  moist  tan-bark. 

3.  The   presence  of  carbon  dioxide  in  considerable 

quantities. 

1  Vitruvius,  p.  186. 

2  Pliny,  Natural  History,  Book  XXXV,  Chap.  IX. 


4  THE  LEAD   AND   ZINC  PIGMENTS. 

7.  That  the  ancients  were  well  acquainted  with  the  first 
requisite  is  evidenced  by  the  descriptions  already  given. 
Pliny  also  in  describing  the  manufacture  of  white  lead 
says,  "It  is  made  from  very  fine  shavings  of  lead  placed 
over  a  vessel  filled  with  the  strongest  vinegar."  * 

Discorides,  writing  in  the  first  or  second  century,  states : 
"  Having  poured  vinegar  .  .  .  into  a  broad -mouthed 
pitcher,  or  an  earthen  jar,  fasten  firmly  a  mass  of  lead 
near  the  top  of  the  jar  upon  a  mat  of  reeds  previously 
stretched  beneath."  2 

In  another  place  he  explains  more  in  detail,  "  Having 
suspended  a  stick  of  wood  about  the  middle  of  the  jar, 
place  the  mat  of  twigs  before  mentioned  upon  it,  in  such  a 
manner  that  it  may  not  touch  the  vinegar." 

8.  The  second  requirement,  that  of  a  gentle  but  long 
continued  source  of  heat,  while  not  mentioned  by  some 
of  the  earlier  writers,  is  specifically  mentioned  by  at  least 
two.     Discorides  states  that  the  manufacture  of  white  lead 
can  be  carried  on  in  the  winter  as  well  as  in  the  summer, 
"  if  you  place  the  jar  over  braziers,  cauldrons  or  furnaces; 
for  heat  applied  to  it  shows  the  same  effect  as  the  sun," 
thus  indicating   that  advantage  was  taken  of   the  sun's 
rays  as  a  source  of  heat.     Galen,  writing  in  the  second 
century,  says  that  white  lead  is  made  by  dissolving  litharge 
in  vinegar,  burying  the  vase  containing  these  substances 
in  dung  for  forty  days.3    Here  we  also  have  a  probable 
source  of  heat  mentioned. 

9.  In   regard    to    carbon   dioxide,   the   third   requisite 
necessary  for  the  proper  manufacture  of  white  lead,  it 
can  be  said  that  none  of  the  ancient  writers  mention  any 
means  of  securing  its  presence  or  in  any  way  indicate  that 

1  Pliny,  Natural  History,  Book  XXXIV,  Chap.  LIV. 

2  Discorides,  De  Materia  Medica. 
8  Hoffmann,  Das  Blei,  p.  42. 


WHITE   LEAD   IN   ANCIENT  TIMES.  5 

carbon  dioxide  or  any  gas  was  necessary  for  the  preparation 
of  ceruse.  This  omission  on  their  part  has  led  some 
modern  writers  to  doubt  that  the  ancients  were  acquainted 
with  what  we  know  as  white  lead.  However,  if  we  con- 
sider the  exceedingly  imperfect  knowledge  that  the 
ancients  had  regarding  the  chemistry  of  the  various  pro- 
cesses they  used  in  their  manufactures,  this  omission  is 
not  to  be  wondered  at,  especially  when  we  consider 
the  impure  nature  of  the  vinegar  or  acetic  acid  in  use  in 
early  times,  due  to  the  crude  and  imperfect  methods  of 
manufacture,  which  necessarily  resulted  in  a  considerable 
amount  of  grape  skins  and  pulp  passing  into  the  expressed 
juice.  These  impurities  naturally  evolved  considerable 
carbon  dioxide  in  the  course  of  their  decomposition,  an 
amount  sufficient  at  least  to  carbonate  a  considerable 
quantity  of  lead.  This  method  of  producing  carbon  diox- 
ide being  so  closely  associated  with  the  natural  fermen- 
tation of  the  grape  juice  into  vinegar,  might  well  pass 
unnoticed  and  uncommented  upon  by  the  ancient  experi- 
menters and  historians.  In  support  of  this  contention, 
Pulsifer  cites  the  following  statement  from  Gentele's 
Lehrbuch  der  Farbenfabrikation  regarding  the  modern 
manufacture  of  white  lead  at  Klagenfurth,  in  Carinthia: 
"  The  acetic  acid  and  the  carbon  dioxide  being  simulta- 
neously produced  by  the  fermentation  of  the  extract  of 

ied  grapes  or  raisins,  or  of  the  residuum  of  grapes  after 
pressing.  Water-tight  boxes  are  prepared  into  which 
the  raisins  or  the  residuum  is  placed;  to  this  is  added  a 
quantity  of  vinegar.  When  subjected  to  heat,  the  vinous 
fermentation  begins  in  the  sweetish  liquor,  producing 
alcohol  and  carbon  dioxide,  and  the  acetic  fermentation 
also  occurs  in  the  alcohol,  producing  acetic  acid." 

Viewing  the  matter  in  this  light,  the  presence  of  carbon 
dioxide  can  be  satisfactorily  accounted  for  in  the  processes 


6  THE  LEAD   AND   ZINC  PIGMENTS. 

used  by  the  ancients,  and  the  product  obtained  by  them 
was  a  true  white  lead;  although  probably  badly  contami- 
nated with  both  the  normal  and  the  almost  insoluble  basic 
lead  acetates. 

It  is  quite  certain  that  white  lead  was  made  in  notable 
quantities  at  the  beginning  of  the  Christian  era.  Accord- 
ing to  the  historians,  Rhodes  was  the  most  important 
seat  of  manufacture,  although  the  industry  was  sufficiently 
notable  in  Corinth  and  Lacedemonia  to  be  mentioned  by 
Pliny. 

10.  Early  Improvements.  Little  practical  advancement 
was  made  in  the  art  of  making  white  lead  for  many  hun- 
dred years  after  the  beginning  of  the  Christian  era.  This 
is  not  to  be  wondered  at  when  we  consider  the  decay  of 
learning  and  the  dismemberment  of  the  Roman  Empire. 
Such  knowledge  as  survived  was  locked  up  in  the  various 
monasteries,  and  it  is  to  the  various  manuscripts  written 
by  the  monks  that  we  must  look  for  our  information. 
Many  of  the  references  that  have  been  found  regarding 
methods  or  recipes  for  the  manufacture  of  white  lead  were 
evidently  copied  from  still  earlier  writings,  which  in  turn 
may  have  been  and  in  fact  probably  were,  taken  from  the 
manuscripts  of  the  Greek  and  Roman  historians  already 
referred  to.  Some  of  the  manuscripts,  however,  seem  to 
be  more  than  copies  and  really  serve  as  a  connecting  link 
between  the  methods  used  by  the  ancients  and  those  in 
use  at  the  present  time,  and  indicate  certain  noteworthy 
improvements  in  the  art.  Especially  are  the  writings  of 
Theophilus  and  Eraclius  of  interest,  as  they  imply  that 
decomposing  horse  dung  came  into  use  during  this  period 
as  a  source  of  gentle  heat  for  carrying  the  reaction  through 
to  completion  and  also  unwittingly  perhaps  as  a  source 
of  carbon  dioxide  gas.  Also  both  writers  mention  the  use 
of  linseed  oil  as  a  vehicle  for  preparing  paints.  Theophi- 


WHITE  LEAD   IN  ANCIENT  TIMES.  7 

lus  in  particular  gave  elaborate  directions  for  the  prepa- 
ration of  linseed  oil  and  the  grinding  of  white  lead  in  oil. 

11.  Effect   of  the  Revival  of  Learning.    The  revival  of 
learning  in  Europe,  beginning  in  the  eleventh  century,  was 
accompanied  by  a  renewed  activity  in  manufactures  and 
scientific  pursuits,  and  the  manufacture  and  use  of  white 
lead  became  an  item  of  importance  throughout  western 
Europe  and  Great  Britain,  although  its  use  was  confined 
almost    entirely    to    paintings    and    church    decorations. 
History  relates  that  the  chapel  of  Saint  Stephen  in  England 
was  rebuilt  in  1352  and  that  all  of  the  painters  in  the  sur- 
rounding country  were  employed  in  its  decoration.     Among 
the  items  for  material  were  the  following : l 

£          8  d 

19  pounds  white  lead  for  priming  at  4d 0  6  4 

4  flagons  of  painter's  oil 0  16  0 

62  pounds  red  lead  at  5d 1  5  10 

J  pound  red  lead 8 

And  again: 

Item :  To  John  Lightgrave 

£      s      d 
51  pounds  white  lead  at  2Jd 0     10    ?i 

53  pounds  white  lead  at  3Jd 0     15      5 

43  pounds  red  lead  at  4d 0     16      6 

3  pounds  white  lead 0       1      0 

The  considerable  variations  in  price  might  indicate  that 
the  use  of  reduced  or  adulterated  white  lead  was  by  no 
means  uncommon  even  at  that  time,  a  fact  which  was 
severely  commented  upon  by  various  writers  at  a  slightly 
later  date. 

12.  The  methods  of  manufacture  described  in  the  various 
authentic  documents  of  the  period,  while  indicating  that  the 

1  Pulsifer,  History  of  Lead,  p.  243. 


8  THE  LEAD   AND   ZINC  PIGMENTS. 

manufacture  was  carried  on  on  a  more  extended  scale  and 
with  a  continual  improvement  in  technical  knowledge, 
still  followed  closely  the  principles  recorded  by  Vitruvius, 
Pliny,  Theophilus,  and  others,  except  that  the  advantages 
resulting  from  the  use  of  stable  manure  as  a  source  of  heat 
were  now  fully  recognized. 

13.  Development  of  the  Lead  Industry  by  the  Dutch.  It 
is  almost  universally  believed  that  the  Dutch  were  the 
inventors  or  originators  of  'the  process  of  manufacturing 
white  lead  by  which  the  larger  part  of  our  white  lead  is  made 
to-day,  viz.,  the  "  Dutch  process,"  the  usual  date  given 
for  the  establishing  of  the  industry  in  Holland  being  1622. 
As  has  been  clearly  shown,  however,  the  industry  did  not 
originate  with  the  Dutch,  but  was  in  general  use  throughout 
western  Europe  prior  to  that  date;  in  fact,  as  Pulsifer 
points  out  in  his  "  History  of  Lead,"  that "  the  description  in 
the  manuscript  of  Theophilus  varies  in  no  important  par- 
ticular from  that  used  by  the  Dutch  in  the  seventeenth 
century,  even  to  the  use  of  stable  litter.  Objection  may 
be  made  to  the  statement  that  The0philus  did  not  secure 
the  necessary  carbon  dioxide  from  the  decomposing  dung, 
neither  did  the  Dutch  in  the  seventeenth  century  depend 
upon  the  decomposition  of  the  ferment  for  this  element,  but 
added  to  the  vinegar  in  the  pots  wine  lees,  bits  of  marble, 
and  other  substances  capable  of  producing  this  necessary 
factor." 

He  states  further  in  the  same  connection, "  it  is  impossible, 
therefore,  that  the  Dutch  invented  a  process  which  is 
clearly  described  in  manuscripts  written  before  the  foun- 
dation of  Amsterdam,  and  it  is  unlikely  that  they  borrowed 
from  the  Arabs  in  Spain  a  method  which  had  been  prac- 
ticed for  more  than  three  hundred  years  in  the  Italian  cities 
with  which  their  neighbors,  the  Flemings,  had  been  in  con- 
stant communication." 


WHITE  LEAD  IN  ANCIENT  TIMES.  9 

14.  Early  Adulteration   of  White   Lead.     Nevertheless 
credit  must  be  given  the  Dutch  for  developing  the  industry 
along  broad  commercial  lines.     In  fact  their  very  eagerness 
to  monopolize  the  white  lead  industry  of  Europe  and  under- 
sell their  competitors,  especially  the  Venetians,  undoubtedly 
led  them  to  adulterate  their  products  with  chalk  and  similar 
materials,  to  the  detriment  of  the  entire  industry.     Zedler 
in  his  Lexicon  states  "  that  the  painter  bought  the  Holland 
ceruse  because  it  was  cheaper,  but  contained  much  chalk, 
whereas  the  Venetian  was  pure,  of  great  enduring  qualities, 
and  kept  white  until  the  last."     Pomet,  chief  druggist  to 
the  French  king,  Louis  XIV,  in  his  complete  "History  of 
Drugs,"  says  that  they  "  used  little  else  in  France  than 
ceruse  de  Holland,   which  was  cheaper,  and  was  much 
esteemed  by  the  painter,  but  in  this  they  were  wrong,  as 
the  Dutch  ceruse  had  so  much  chalk  in  it  that  it  was  of  no 
long  duration." 

15.  Von  Justi,  writing  in  1758,  states,  "  white  lead  is  in 
much  greater  demand  than  one  would  suppose;  the  man- 
ufacture is  not  enough  to  supply  the  demand  in  this  Prus- 
sian kingdom.     It  is  best  not  to  falsify  white  lead,  but  to 
prepare  it  pure.     In  Holland  and  England  we  find  that  a 
good  proportion  of  chalk  is  added,  and  so  we  have  been 
obliged  to  do  this  that  we  may  sell  it  at  the  same  price. 
Only  the  Venetian  is  wholly  pure  and  on  that  account  it  is 
much  sought  after  and  is  sold  at  a  higher  price." 

16.  Manufacture  of  White  Lead  in  Seventeenth  Century. 
Sir  Philiberto  Vernatti,  writing  in  1678,  describes  with  much 
skill  and  accuracy  the  process  used  by  the  Venetians  at  that 
time   for  making   white   lead.    His  description  indicates 
that  they  had  reached  a  high  state  of  skill  in  the  art,  such 
as  could  only  have  been  obtained  by  many  years  of  intelli- 
gent and  continued  activity  in  the  industry,  and  which 
should  be  conclusive  evidence  that  they  were  well  versed 


10  THE  LEAD  AND   2INC  PIGMENTS. 

in  the  manufacture  of  white  lead  prior  to  the  date  ascribed 
to  the  Dutch.  It  is  also  to  be  noted  that  Vernatti's  descrip- 
tion differs  in  no  important  detail  from  the  process  now 
known  as  the  Dutch  process.  He  says:  "  First,  pigs  of 
clean  and  soft  lead  are  cast  into  thin  plates  a  yard  long, 
six  inches  wide,  and  to  the  thickness  of  the  back  of  a  knife. 
These  are  rolled  with  some  art  round,  but  so  as  the  surfaces 
nowhere  meet  to  touch,  for  where  they  do,  no  ceruse  grows. 
Thus  rolled,  they  are  put  each  in  a  pot  just  capable  to  hold 
one,  up-held  by  a  little  bar  from  the  bottom,  that  it  comes 
not  to  touch  the  vinegar  which  is  put  into  each  pot  to  effect 
the  corrosion.  Next  a  square  bed  is  made  of  new  horse- 
dung,  so  big  as  to  hold  twenty  pots  abreast  and  to  make  up 
the  number  four  hundred  in  one  bed.  Then  each  pot  is 
covered  with  a  plate  of  lead,  and  lastly  all  with  boards,  as 
close  as  conveniently  can  be.  This  repeated  four  times  makes 
one  'heap'  so  called,  containing  sixteen  hundred  pots.  After 
three  weeks  the  pots  are  taken  up,  the  plates  unrolled,  laid 
upon  a  board,  and  beaten  with  battledoors  till  all  the  flakes 
come  off,  which  if  good,  prove  thick,  hard  and  weighty;  if 
otherwise,  fuzzy  and  light,  or  sometimes  black  and  burned 
if  the  dung  prove  not  well  ordered;  and  sometimes  there 
will  be  none.  From  the  beating  table  the  flakes  are  carried 
to  the  mill,  and  with  water  ground  between  mill-stones 
until  they  be  brought  to  an  almost  impalpable  fineness; 
after  which  it  is  moulded  into  small  parcels  and  exposed  to 
the  sun  to  dry  until  it  be  hard,  and  so  fit  for  use." 

17.  "  Accidents  to  the  work  are;  that  two  pots  alike 
ordered,  and  set  one  by  the  other,  without  any  possible 
distinction  of  advantage,  shall  yield,  the  one  thick  and  good 
flakes,  the  other  few  and  small  or  none,  which  happeneth 
in  greater  quantities,  even  over  whole  beds  sometimes. 
Sometimes  the  pots  are  taken  up  all  dry  and  so  some- 
times prove  best;  sometimes  again  they  are  taken  up  wet. 


WHITE    LEAD   IN   ANCIENT  TIMES.  11 

Whether  this  arises  from  the  vapors  coming  from  below, 
or  by  the  moisture  that  is  squeezed  out  by  the  weight  of 
the  pots,  we  cannot  discover.  This  we  observe,  that  the 
plates  which  cover  the  pots  yield  better  and  thicker  flakes 
than  do  the  rolls  within ;  and  the  outsides  next  the  planks, 
bigger  and  better  than  the  insides." 

18.  The  Dutch  Method  of  Manufacture.  The  above 
description  indicates  that  the  Venetians  were  cognizant 
of  the  same  obstacles  and  drawbacks  that  confront  the 
corroder  to-day,  and  that  the  above  method  is  very  closely 
similar  to  the  Dutch  process  as  described  by  the  Dutch 
writer,  Jars,  approximately  one  hundred  years  later.  Jars 
is  accredited  as  a  most  careful  and  intelligent  observer, 
and  his  statements  as  given  by  Pulsifer,1  probably  repre- 
sented very  closely  the  methods  followed  by  the  Dutch  at 
that  time. 

"  The  lead  was  first  cast  in  thin  sheets  which  were  rolled 
in  a  spiral  and  placed  in  earthen  pots,  seven  to  eight  inches 
high  and  four  to  five  inches  in  diameter,  made  wider  at  the 
top  than  at  the  bottom.  To  prevent  the  lead  from  falling 
to  the  bottom,  they  placed  inside  the  pot,  and  at  about  one- 
third  of  its  depth,  a  piece  of  wood,  cut  the  length  of  the 
diameter  of  the  pot.  This  was  the  Rotterdam  method. 
At  Amsterdam,  the  manufacturers  had  moulded  in  the 
inside  of  the  pot,  and  at  about  one-third  its  height,  three 
little  points  which  served,  instead  of  wood,  to  support  the 
lead.  The  stacks  were  built  in  one  range  of  four,  each 
being  about  fifteen  feet  square.  After  the  pots  had  been 
filled  up  to  an  indicated  point  with  vinegar,  and  the  spiral 
of  lead  placed  in  position  in  each  pot,  they  were  arranged 
in  rows  in  the  stack  upon  a  bed  of  dung,  four  feet  thick; 
the  pots  were  placed  together  as  closely  as  possible,  and 
when  the  bed  was  covered  with  the  pots,  plates  of  lead  were 
1  Pulsifer,  History  of  Lead,  p.  267. 


12  THE  LEAD   AND   ZINC  PIGMENTS. 

laid  upon  them  and  the  whole  covered  with  boards.  These 
boards  were  then  covered  with  dung,  and  another  tier  of 
pots  placed  as  before,  filled  with  vinegar  and  lead,  and 
covered  in  the  same  manner.  This  was  repeated  until  five 
tiers,  or  layers,  were  built  up.  The  lead  was  left  in  the 
stacks  from  four  to  five  weeks  according  to  the  season  and 
the  quality  of  the  dung.  In  one  of  the  layers  which  Jars 
saw  opened,  he  remarked  that  the  action  did  not  appear  to 
be  equally  satisfactory.  In  some  the  sheets  of  lead  were 
entirely  corroded,  in  others  the  operation  was  partial  only, 
while  in  a  few  the  surface  of  the  sheets  was  only  slightly 
attacked.  This  unequal  action  he  attributed  to  the  dung 
heating  more  in  some  parts  than  in  others.  The  sheets 
covering  the  pots  formed  a  crust  or  scale,  harder  and  more 
compact,  and  were  put  to  one  side  to  be  used  in  the  manu- 
facture of  blanc  de  plomb.  When  the  dung  had  been  used 
several  times,  it  was  replaced  by  new;  that  rejected  was 
sold  to  be  used  as  a  fertilizer.  The  sheets  which  were  par- 
tially converted  were  taken  from  the  pots  and  placed  upon 
heavy  tables,  and  beaten  with  mallets  to  separate  the  white 
lead  from  the  unconverted,  care  being  taken  to  sprinkle  it 
with  water  from  time  to  time  to  abate  the  dust.  The 
ceruse  was  now  removed  to  the  mills  where  in  Amsterdam 
it  was  twice,  and  in  Rotterdam  three  times  ground  in 
water,  the  mills  being  placed  one  above  another,  the  lead 
falling  from  the  upper  mill  directly  to  the  one  below  it, 
finally  passing  to  a  tub  placed  below  to  receive  it. 

19.  "  The  workmen  having  in  charge  the  grinding  of  the 
lead  fed  the  ceruse  from  the  tubs  with  a  ladle  into  the 
eye  of  the  stone,  adding  from  time  to  time  chalk  in  desired 
proportions  to  form  the  mixture.  This  mixture  formed 
the  ceruse.  The  blanc  de  plomb,  which  was  white  lead,  was 
ground  without  the  admixture  of  any  substance,  and 
being  harder  and  requiring  to  be  finer  and  ground  with 


WHITE   LEAD    IN   ANCIENT  TIMES.  13 

more  care,  the  mills  could  produce  but  ten  quintals  per 
day,  while  of  the  ceruse  fifteen  quintals  were  turned  out. 

"The  last  operation,  drying,  was  managed  as  follows: 
the  ceruse  in  a  pulpy  state  was  filled  into  unglazed  earthen 
pots,  in  shape  like  a  section  of  an  inverted  cone;  these 
pots  were  placed  upon  long  wooden  shelves,  in  a  long 
and  narrow  building,  in  the  sides  of  which  a  great  number 
of  doors  were  provided  to  open  and  close  at  pleasure, 
to  shield  the  ceruse  from  sun  and  rain  which  would  impair 
its  fcolor.  After  five  or  six  weeks  the  pots  were  removed, 
and  the  ceruse  was  turned  out,  the  contents  of  each  pot 
forming  a  conical  mass  or  loaf;  when  perfectly  dry  this 
was  trimmed,  tied  up  in  blue  paper  and  packed  in  barrels 
for  market." 

20.  English  Method  of  Manufacture.  The  methods 
employed  for  the  manufacture  of  white  lead  in  England 
were  substantially  the  same  as  those  in  use  in  Holland. 
In  1787,  however,  one  Richard  Fishwick  obtained  a  patent 
for  the  use  of  spent  tan-bark  in  the  place  of  stable  manure, 
claiming  that  the  tan-bark  communicated  a  more  equable 
and  uniform  degree  of  heat  to  the  lead  and  vinegar.  This 
date  undoubtedly  approximately  marks  the  introduction 
of  this  important  improvement  which  may  be  considered 
the  link  connecting  these  earlier  methods  with  the  Dutch 
process  as  conducted  to-day. 


CHAPTER  II. 

DEVELOPMENT  OF  THE  WHITE    LEAD    INDUSTRY    IN    THE 
UNITED   STATES. 

21.  Early  Use  of  White  Lead.   Pulsifer  in  his  "  History 
of  Lead  "  *  clearly  explains  the  attitude  of  the  early  Amer- 
ican colonists  toward  the  use  of  white  lead  and  of  paints 
in  general. 

"  There  was  but  little  need  for  the  establishment  of 
white-lead  factories  in  the  United  States  until  after  the 
Revolution.  The  simple  habits  of  the  first  settlers,  their 
poverty  and  their  struggles  for  subsistence  prohibited  the 
use  of  paints  for  decorative  purposes,  while  the  abundance 
of  timber  rendered  it  unnecessary  to  be  at  any  great 
expense  to  preserve  it  from  the  destructive  action  of  the 
elements.  The  use  of  paint,  therefore,  was  discour- 
aged by  the  early  settlers.  Bishop  relates  the  case  of  the 
Rev.  Thomas  Allen,  of  Charlestown,  near  Boston,  who 
was  '  called  to  account '  in  1639  for  having  paint  about 
his  dwelling.  The  reverend  gentleman  secured  immunity 
from  correction  by  assuring  the  authorities  of  his  condem- 
nation of  the  practice  of  using  paint,  and  by  proving  that 
the  offensive  substance  had  been  applied  by  a  former 
proprietor,  and  was  there  when  he  took  possession  of  the 
premises. 

22.  "The  dwellings  of  the  early  settlers  were  generally 
of   wood,    unpainted    on    the    outside    and    inside.      The 
interior  walls  were  occasionally  whitewashed,  but  beyond 
this  no  decoration  was  to  be  observed.     The  first  church 
in  Boston  (destroyed  by  fire  in  1711)  was  never  painted, 

1  Page  313. 
14 


DEVELOPMENT   OF  WHITE   LEAD  INDUSTRY.         15 

it  is  said,  inside  or  outside.  In  1705,  according  to  Bishop, 
the  coat  of  arms  of  Queen  Anne,  in  the  Court  House  at 
Salem,  Mass.,  was  ordered  to  receive  a  '  coloured  cover- 
ing/ which  is  said  to  be  the  first  reference  to  art  in  that 
quarter.  A  list  of  mechanics  made  in  1670,  in  Massachu- 
setts, fails  to  show  the  name  of  a  single  painter.  Painters' 
colors,  however,  were  for  sale  in  Boston  in  1714." 

23.  The  First  White  Lead  Plant.  It  is  not  surprising, 
therefore,  that  the  development  of  the  white  lead  industry 
was  delayed  for  a  great  many  years  after  numerous  other 
industries  had  secured  a  foothold  in  the  colonies.  Even 
the  actual  date  of  the  establishment  of  the  first  white 
lead  plant  is  uncertain.  Credit  for  the  introduction  of  the 
industry  into  this  country  is  ascribed  to  Samuel  Wetherill 
&  Sons,  who  in  1777  or  shortly  after  had  established  a 
factory  in  Philadelphia  for  the  manufacture  of  chemical 
products  and  were  known  as  importers  and  dealers  in  dye- 
stuffs,  various  chemicals,  and  white  and  red  lead.  Mr.  W. 
H.  H.  Wetherill,  a  descendant  of  the  fourth  generation, 
fixes  the  date  of  domestic  production  and  the  actual 
establishment  of  the  industry  by  Wetherill  &  Sons  at  1804. 
History  relates  that  the  factory  was  burned  shortly  after 
it  began  operation  by  an  Englishman  who  sailed  for  London 
the  day  following  the  fire.  The  factory  was  rebuilt  in 
1808  or  1809,  despite  the  threats  of  English  white  lead 
agents  that  they  would  crush  the  enterprise,  and  which 
history  relates  they  endeavored  to  accomplish  until  the 
war  of  1812  forced  them  to  retire  from  the  American 
markets  and  assured  the  prosperity  of  the  enterprise. 
Wetherill  &  Sons  undoubtedly  used  the  Dutch  process,  and 
utilized  horse  dung  as  the  source  of  heat  and  carbon  dioxide. 
Pulsifer  records  that  they  took  out  several  patents  and 
made  numerous  improvements  in  both  the  white  and  red 
lead  industries. 


16 


THE   LEAD   AND   ZINC  PIGMENTS. 


DEVELOPMENT   OF   WHITE   LEAD   INDUSTRY.      .    17 

24.  Coxe  in  an  official  report  to  the  Secretary  of  the 
Treasury  in   1810  states   that    there  was  only  one   lead 
factory  in  operation  at  that  date  and  that  369  tons  were 
produced  in  that  year.     This  report  undoubtedly  refers  to 
the  Wethcrill  plant. 

25.  Effect  of  the  War  of  1812.     The  war  of  1812  made 
the  white  lead  industry  a  very  profitable  one,  and  it  is  only 
natural  that  the  industry  developed  rapidly.     The  second 
plant  was  built  in  Philadelphia  about  1812  by  an  English- 
man by  the  name  of  Smith,  who  was  succeeded  in  1813  by 
one  Joseph  Richards,  who  in  1819-20  disposed  of  the  con- 
trolling interest   to   M.  Lewis  &  Co.     John   Harrison,  a 
chemical   manufacturer,  also  of   Philadelphia,  began  the 
corroding   of   white   lead    by   the   Dutch   process   almost 
immediately   after  the   rebuilding  of  his  chemical  works 
which  were  destroyed  by  fire  in  1806.     The  actual  date  of 
operation,  however,  is  unknown. 

26.  Other  Early  Manufacturers.     The    manufacture    of 
white  lead  was  begun  in  Pittsburg  not  far  from  1810-12 
by  Bielin  &  Stevenson,  and  at  about  the  same  time  by 
Trevor,  Pettigrew  &  Provost,  who,  however,  did  not  remain 
in  business  long.    In  1815  a  factory  was  established  in  Cin- 
cinnati by  the  Cincinnati  Manufacturing  Company.    Bishop 
in  his  " History  of  American  Manufactures  "states  that 
a  corroding  plant  was  established  in  New  York  in  1820, 
but  does  not  state  the  name  of  the  company.     The  Brook- 
lyn White   Lead  Works  was  incorporated  not   far  from 
1825.     This  firm  first  endeavored  to  manufacture  white 
lead  by  a  quick  process  said  to  have  been  devised  by  a 
Dr.  Vanderberg  of  Albany,  who  was  the  originator  of  the 
company.     The    process,   like    many    later    ones,   proved 
unsuccessful  and  was  abandoned  for  the  old  Dutch  process 
about  1830,  horpe  manure  being  used  as  the  fermenting 
material.     In  1832  Mr.  Augustus  Graham,  an  active  part- 


18  THE   LEAD   AND   ZINC  PIGMENTS. 

ner  of  the  company,  went  to  England  and  there  secured 
employment  as  an  ordinary  workman  in  one  of  the  best 
equipped  corroding  plants  and  learned  their  process  and 
methods  in  detail  and  which  were  introduced  in  his  own 
plant  on  his  return  to  this  country,  the  most  important 
improvement  being  the  substitution  of  tan-bark  for  horse 
manure. 

27.  Adoption  of  Uniform  Scale  of  Prices.  The  establish- 
ment of  numerous  other  white  lead  plants  and  the  opening 
up  of  new  lead  ore  fields  caused  a  big  decline  in  the  price 
of  both  metal  and  white  lead,  and  Pulsifer  relates  that  "  In 
1830  the  manufacturers  of  the  Eastern  cities  of  the  United 
States  found  it  necessary,  owing  to  very  strong  competition, 
and  probably  overproduction,  to  enter  into  an  agreement 
for  the  purpose  of  maintaining  uniform  and  profitable 
prices.  By  the  terms  of  this  agreement  each  factory 
(there  were  eight  at  that  time  east  of  the  Alleghanies) 
had  the  privilege  of  appointing  an  agent  in  eleven  principal 
markets  in  the  Eastern  States,  from  Portland  to  New 
Orleans.  These  agents  were  to  receive  a  commission  of 
five  per  cent.  The  prices  and  terms  fixed  by  this  agree- 
ment were  as  follows: 

Dry  white  lead 8  cents  per  pound 

Pure  lead,  ground  in  oil 9  cents  per  pound 

Potters'  red  lead 6  cents  per  pound 

Glassmakers'  red  lead 7|  cents  per  pound 

*  The  terms  were : 

For  quantities  amounting  to 
Less  than  $300,  6  months. 

From  $300  to  $500,  6  months  and  1  per  cent  discount. 
From  $500  to  $800,  6  months  and  2  per  cent  discount. 
From"  $800  and  upwards,  6  months  and  3  per  cent  dis- 
count. 


DEVELOPMENT   OF   WHITE   LEAD   INDUSTRY.         19 

"  It  was  stipulated  that  these  amounts  were  to  be  pur- 
chased at  one  time  to  entitle  the  buyer  to  these  terms. 

28.  "The  parties  to  this  agreement  bound  themselves 
in  the  sum  of  two  thousand  dollars,  to  be  considered  and 
treated  as  stipulated  damages,   for  the   full  and   faithful 
performance  of  the  agreement,  and  ninety  days'  notice 
was  required  to  be  given  of  an  intention  to  withdraw. 

"  The  signers  of  this  agreement  were  Lewis  &  Company, 
Wetherill  &  Sons,  Harrison  Brothers,  of  Philadelphia; 
Hinton  &  Moore,  of  New  York,  who  were  possibly  selling 
agents  for  the  Union  Company,  the  Brooklyn  White  Lead 
Company,  of  Brooklyn,  New  York;  and  Francis  Peabody, 
and  the  Salem  Lead  Manufacturing  Company  of  Salem, 
Massachusetts." 

The  production  of  white  lead  at  this  date  had  reached 
about  three  thousand  tons  and  in  1840  to  about  five  thou- 
sand tons. 

29.  Formation  of  New  Companies.   Between   1840  and 
1850  the  white  lead  industry  increased  rapidly.    The  follow- 
ing companies  were  established  at  about  this  period: 

Eckstein  White  Lead  Company,  Cincinnati,  1837. 

Atlantic  White  Lead  Company,  of  New  York,  1842. 

Jewett  Lead  Works,  of  New  York,  1844. 

Ulster  White  Lead  Company,  Saugerties,  N.  Y.,    

Fahnestock  White  Lead  Works,  Pittsburgh,  1844. 

Eagle  White  Lead  Works,  Cincinnati,  

The  Collier  White  Lead  and  Oil  Works,  St.  Louis,  1851. 

It  is  probable  that  the  annual  production  of  white  lead 
in  1850  was  about  nine  thousand  tons.  Between  1850 
and  1860  there  was  little  development  in  the  industry  as 
far  as  the  building  of  new  plants  was  concerned.  The 
practice  of  adulterating  white  lead  had  grown  to  such  an 
extent  that  but  little  room  was  left  for  substantial  increase 


20  THE    LEAD   AND    ZINC   PIGMENTS. 

in  the  manufacture  of  white  lead,  notwithstanding  the 

increase  in  population  and  wealth  of  the  country,  and  the 

I/  production  by  1860  was  only  about  fifteen  thousand  tons. 

30.  Effect  of  the  Civil  War.   The  enormous  demand  for 
metallic  lead  at  the  beginning  of  the  Civil  War  checked  the 
growth  of  the  white  lead  industry  for  a  time,  although  the 
differential    between    pig   lead    and    white    lead    reached 
almost  ten  cents  in  1864.     This  enormous  profit  stimulated 
the  erection  of  several  new  plants  toward  the  close  of  the 
war,  and  the  period  immediately  following  was  marked  by 
a  great  development  of  the  industry.     Among  the  more 
important  plants  erected  during  this  period  are : 

S.  B.  Cornell  &  Son,  Buffalo,  1861. 

St.  Louis  Lead  and  Oil  Company,  St.  Louis,  1865. 
Southern  White  Lead  Company,  St.  Louis,  1866. 
D.  B.  Shipman  White  Lead  Works,  Chicago,  1865. 

Western  White  Lead  Company,  Chicago,      

Davis  Chambers  Lead  Company,  Pittsburgh,  1866. 
Beymer,  Bauman  &  Co.,  Pittsburgh,  1867. 

J.  H.  Morley  White  Lead  Works,  Cleveland,  1867. 

Bradley  White  Lead  Works,  Brooklyn,          

Salem  Lead  Works,  Salem,  Mass.,  1868. 

31.  Patents  Issued.   Pulsifer  states  that  not  less  than 
forty  patents  were  issued  during  this  decade  (1860-1890) 
for  improvements  in  the  manufacture  of  white  lead,  most 
of  them  modifications  of  the   Dutch  process  or  precipi- 
tation processes.     None  of  them,  however,  as  far  as  can 
be   learned  proved  to  be  of  any  economic  value.     The 

^/production  of  white  lead  in  1870  has  been  estimated  at 
35,000  tons. 

32.  Between  1870  and  1880  the  industry  continued  to 
show  a  healthy  development,  but  was  along  the  lines  of 
expansion  and  increase  of  facilities  in  the  plants  already 


DEVELOPMENT   OF   WHITE  LEAD   INDUSTRY.        21 


FIG.  3.  —  LEAD  BUCKLE. 


22  THE   LEAD   AND   ZINC  PIGMENTS. 

established  rather  than  in  the  building  of  new  plants. 
Thirty-five  patents  were  issued  for  improvements  in  the 
manufacture  of  white  lead  during  this  decade,  fifteen  of 
which  were  for  new  processes  the  majority  of  which  were 
tried  out  on  a  commercial  scale  but  like  the  preceding  inven- 
tions were  unsuccessful  and  were  abandoned  after  entailing 
more  or  less  loss  upon  the  promoters.  Since  that  date 
there  have  been  comparatively  few  attempts  to  develop 
new  processes  on  a  commercial  scale,  although  two  at 
least  have  proven  highly  successful  and  are  being  carried 
out  on  a  large  scale,  viz.,  the  Carter  process  and  the  Mild 
process,  formerly  known  as  the  Rowley  process,  both  of 
which,  together  with  the  Matheson  process  and  the  Bailey 
process,  will  be  discussed  at  length  in  subsequent  chapters. 
33.  Improvements.  Since  the  substitution  of  tan-bark 
for  stable  litter  in  1832  by  Graham  there  have  been  very 
few  improvements  made  in  the  methods  or  details  of  the 
Dutch  process,  and  these  few  relate  chiefly  to  improve- 
ments in  the  washing,  screening,  and  drying  of  the  white 
lead  rather  than  in  the  principles  or  details  of  corrosion. 
One  or  two  companies  are  attempting  to  separate  the 
corrosions  from  the  metallic  cores  by  a  dry  process  with- 
out washing  the  lead  at  all  and  the  residual  acetates 
remaining  in  the  white  lead  are  given  a  treatment  with 
ozonized  air  to  convert  them  into  a  less  active  form. 
One  of  the  newest  attempted  innovations  is  the  use  of 
glass  corroding  pots. 


CHAPTER  III. 

DEVELOPMENT    OF    THE  WHITE    LEAD    INDUSTRY  IN  THE 
UNITED   STATES  (Continued). 

34.  Formation  of  National  Lead  Trust.    In   1887   there 
was  formed  an  organization  known  as  the  National  Lead 
Trust,  capitalized  at  $90,000,000,  which  according  to  the 
agreement  and  by-laws  was  organized  for  the  purpose  of 
securing  intelligent  cooperation  in  the  business  of  smelt- 
ing,   refining,    corroding,    manufacturing,    vending,    and 
dealing  in  lead  and  all  its  products  and  canying  on  all 
other  business  incident  thereto.     The  corporations  form- 
ing the  trust  were : 

The  Bradley  White  Lead  Company. 

Anchor  White  Lead  Company. 

The  St.  Louis  Smelting  and  Refining  Company. 

The  St.  Louis  Lead  and  Oil  Company. 

Brooklyn  White  Lead  Company. 

Jewett  White  Lead  Works. 

The  J.  H.  Morley  Lead  Company. 

35.  Absorption  of  Other  Companies.   Within  three  years 
from  the  time  the  National  Lead  Trust  was  formed  there 
had  been  drawn  into  and  absorbed  by  the  trust  accord- 
ing to  the  evidence  in  the  case  of  the  National  Lead  Com- 
pany v.  S.  E.  Grote  Paint  Store  Company,  Supreme  Court 
of  Missouri,  1898,  in  addition  to  those  enumerated  above: 

The  National  Lead  and  Oil  Company  of  New  York, 
Ulster  Lead  Company. 
Union  Lead  Company. 

23 


24  THE   LEAD   AND    ZINC  PIGMENTS. 

S.  G.  Cornell  Lead  Company. 

Atlantic  White  Lead  Company. 

Davis  Chambers  Lead  Company. 

National  Lead  and  Oil  Company  of  Pennsylvania. 

Armstrong-McKelvey  Lead  Company. 

Fahnestock  White  Lead  Company. 

John  T.  Lewis  &  Brothers. 

Eckstein  White  Lead  Company. 

Kentucky  Lead  Company. 

Maryland  White  Lead  Company. 

McBirney- Johnson  Company. 

Salem  Lead  Company. 

Collier  White  Lead  and  Oil  Company. 

Missouri  Lead  and  Oil  Company. 

Red  Seal  Castor  Oil  Company. 

Southern  White  Lead  Company  of  Missouri. 

W.  H.  Gregg  White  Lead  Company. 

36.  Dissolution   of  National   Lead   Trust.   In    1891    the 
National  Lead  Trust  was  dissolved.     President  Thompson 
testified  that  the  reasons  which  led  to  the  dissolution  and 
termination  of  the  trust  were: 

"  Mainly l  because  there  had  been  laws  passed  by  the 
United  States  and  a  number  of  States  that  were  inimical 
to  that  form  of  organization  and  a  great  public  prejudice 
had  been  aroused  which  seriously  affected  the  value  of 
the  shares  of  a  trust.  .  .  .  Besides  the  capitalization  of 
the  National  Lead  Trust  was  excessive." 

37.  Formation  of  National  Lead  Company.   In  December 
of  that  year    (1891)    the  National   Lead   Company   was 
organized  with  a  capital  of  $30,000,000.     President  Thomp- 
son's  report   to    the  stockholders  of   the  National  Lead 

1  Statement,  briefs,  and  opinion  of  the  Court,  National  Lead  Com- 
pany v.  S.  E.  Grote  Paint  Store  Company,  St.  Louis  Court  of  Appeals, 
p.  3. 


I  T 


DEVELOPMENT   OF   WHITE   LEAD   INDUSTRY.         25 

Company,  February  16,  1893,  states  that  "  This  company 
was  organized  for  the  purpose  of  taking  over  all  the  assets 
of  the  National  Lead  Trust." 

38.  According  to  the  testimony  in  the  case  above  cited 
(redirect  examination  of   President  Thompson,  page  30) 
the  certificate  holders  of  the  National  Lead  Trust  sur- 
rendered their  trust  certificates  in  the  National  Lead  Trust 
and  received  in  exchange  therefor  stock  in  the  National 
Lead  Company,  the  certificate  holders  receiving  one  share 
of  common  stock  and  one  share  of  preferred  stock  in  the 
National  Lead  Company  for  every  six  certificates  in  the 
National  Lead  Trust  and  thirty  cents  cash. 

39.  Different  Branches  of  the  National  Lead  Company. 
The  report  also  shows  that  the  National  Lead  Company 
had  the  following  branches  :  * 

Atlantic  Branch,  New  York  City,  proprietors  of  - 
Atlantic  White  Lead  and  Linseed  Oil  Works. 
Jewett  White  Lead  Works. 
Brooklyn  White  Lead  Works. 
Bradley  White  Lead  Works. 
Union  White  Lead  Works. 
Lenox  Smelting  Works. 
Ulster  Lead  Works. 

Boston  Branch,  Boston,  Mass.,  proprietors  of  — 

Salem  Lead  Works. 
Buffalo  Branch,  Buffalo,  N.  Y.,  proprietors  of- 

Cornell  Lead  Works. 
Baltimore  Branch,  Baltimore,  Md.,  proprietors  of  — 

Maryland  WThite  Lead  Works. 
Cleveland  Branch,  Cleveland,  Ohio,  proprietors  of  — 

J.  H.  Morley  Lead  Works. 

1  Statements,  briefs,  and  opinion  of  the  Court,  National  Lead  Com- 
pany v.  S.  E.  Grote  Paint  Store  Company,  St.  Louis  Court  of  Appeals, 
p.  5.  Also  Appellants  Abstract  of  the  Record,  Appeal  from  the  Circuit 
Court,  pages  83  to  91. 


26  THE   LEAD   AND    ZINC  PIGMENTS. 

Cincinnati  Branch,  Cincinnati,  Ohio,  proprietors  of  — 
Eckstein  White  Lead  Works. 
Anchor  White  Lead  Works. 

Louisville  Branch,  Louisville,  Ky.,  proprietors  of  — 
,  Kentucky  Lead  and  Oil  Works. 
American  White  Lead  Works. 

Chicago  Branch,  Chicago,  111.,  proprietors  of  — 
Southern  White  Lead  Works. 
D.  B.  Shipman  White  Lead  Works. 

St.  Louis  Branch,  St.  Louis,  Mo.,  proprietors  of  — 
St.  Louis  Lead  and  Oil  Works. 
Collier  White  Lead  and  Oil  Works. 
Southern  White  Lead  Works. 
Red  Seal  Castor  Oil  Works. 

John  T.  Lewis  &  Brothers  Company,  Philadelphia. 
Western  White  Lead  Company,  Philadelphia. 

National  Lead  and  Oil  Company  of  Pennsylvania,  Pitts 

burg,  proprietors  of  - 

Armstrong-McKelvey  Lead  and  Oil  Works. 
The  Beymer-Bauman  Lead  Works. 
Davis  Chambers  Lead  Works. 
Fahnestock  White  Lead  Works. 
Pennsylvania  White  Lead  Works. 
American  Oxide  Works. 

Also  St.  Louis  Smelting  and  Refining  Company,  St.  Louis, 

Mo.,  proprietors  of  - 

St.  Louis  Smelting  and  Refining  Works,  St.  Louis,  Mo. 
Harrison  Reduction  Works,  Leadvilie,  Colo. 
Rio  Grande  Smelting  Works,  Socorro,  New  Mexico.     • 
St.  Louis  and  Zacatecas  Ore  Company,  Jiminez,  Mexico. 

40.   Operation  of  Factories.   This  report  goes  on  to  state 
that  "  White  lead  factories  disadvantageously  located,  or 


DEVELOPMENT   OF   WHITE   LEAD   INDUSTRY.         27 

unable  from  any  cause  to  make  their  goods  on  an  economic 
basis,  have  been  discontinued,  while  others  have  been 
greatly  enlarged,  so  that  the  capacity  for  production  of  all 
classes  of  goods  manufactured  by  the  company  has  been 
decidedly  increased." 

41.  Independent  Companies.   While  the  National  Lead 
Company  owned  or  controlled  a  large  majority  of  the  white 
lead  plants  of  this  country,  there  were  several  which  main- 
tained an  independent  existence,  the  more  important  of 
which  were  the  Wetherill  plant  of  Philadelphia;  the  Carter 
Company  of  Omaha  and  Chicago;  Nevin,  of  Pittsburg;  the 
Eagle  Lead  Company  of  Cincinnati,  Ohio;  the  Gebhardt 
Company,  of  Dayton,  Ohio;  and  the  Pioneer  of  San  Fran- 
cisco.    Several    of    these    however,    were    of    veiy    small 
capacity. 

42.  The  Bailey  Process.    In  1901  the  Union  Lead  and  Oil 
Company  of  New  York  was  organized  and  a  plant  of  an 
intended  yearly  capacity  of  15,000  tons  was  built,  which 
was  to  manufacture  white  lead  by  the  Bailey  process,  and 
represented  an  investment,  it  is  said,  of  not  far  from  one 
million  dollars. 

43.  The  essential  features  of  this  process  were  the  exten- 
sion of  the  surface  exposed  to  attack  by  the  corroding 
vapors.     "  In  this  process  the  melted  lead  was  forced  by  its 
own  gravity  through  a  perforated  plate  of  thin  steel,  which 
forced  it  into  threads  or  hairs  about  one  one- thousandth  of 
an  inch  in  diameter.     The  lead  solidified  and  cooled  almost 
as  soon  as  it  passed  the  plate,  and  was  piled  on  long,  shallow 
trays  with  slat  bottoms.     Each  of  these  trays  as  it  received 
its  charge  was  run  back  automatically  into  place  in  a 
suitably  constructed  bin  or  rack.     When  all  the  trays  in  this 
rack  had  been  charged  with  the  fibrous  lead  the  process  of 
corrosion  began.     Mingled  vapors  of  acetic  acid,  moisture, 
air,  and  purified  carbonic  acid  gas  were  blown  in  through 


28 


THE   LEAD   AND    ZINC  PIGMENTS. 


FIG.  4.  —  LEAD  FIBRES.  —  BAILEY  PROCESS. 


DEVELOPMENT   OF   WHITE   LEAD   INDUSTRY.         29 

suitable  openings  at  the  bottom  and  sides  of  the  rack,  and 
after  circulating  freely  through  the  mass,  finally  escaped. 
The  temperature  meanwhile  was  maintained  automatically 
at  the  degree  most  favorable  to  satisfactory  corrosion." 

Corrosion  was  completed  in  about  three  days.  The 
product  was  disintegrated,  separated  from  the  uncorroded 
lead,  washed  and  dried  in  the  usual  manner. 

44.  The  United  Lead  Company.   Before  the  plant  was 
operated  at  full  capacity  it  was  taken  over  at  a  much 
higher  figure  by  an  organization  known  as  United  Lead 
Company,  a  corporation  organized  in  June,  1904,  which  in 
substance  wras  a  subsidiary  corporation  of  the  American 
Smelting  and  Refining  Company,  who  presumably  desired 
more  suitable  or  at  least  other  outlets  for  the  pig  lead 
obtained  in  their  smelting  operations.     The  United  Lead 
Company  also  acquired  the  Gebhardt  plant,  the  recently 
built  plant  of  the  Boston-Chadwick  Company,  the  Selby 
plant  of  San  Francisco,  and  the  McDougall  White  Lead 
Company  of  Buffalo,  formerly  known  as  the  Kellogg  & 
McDougall  Company,   which   operated    under  what  was 
substantially  the  Carter  process. 

45.  The  Bailey  plant  apparently  proved  a  colossal  failure, 
as  it  was  shortly  afterwards  abandoned.     This  left  the 
United  Lead  Company  with  an  outlet  for  only  about  one- 
half  of  the  tonnage  capacity  anticipated,  and  did  not  render 
them  the  formidable  rival  of  the  National  Lead  Company 
that  was  anticipated. 

46.  Growth  of  United  Lead  Company.   Further  means 
were,  taken  by  the  United  Lead  Company  by  securing  some 
of  the  highest  talent  in  the  white  lead  industry  with  a  view 
of  constructing  enormous  Dutch  process  corroding  plants 
in  different  sections  of  the  country,  as  there  were  no  more 
independent  plants  that  could  be  acquired  at  anything  like 
reasonable  figures,  the  Sterling  and  Davis  white  lead  com- 


30  THE  LEAD   AND   ZINC  PIGMENTS. 

panies  having  been  purchased  by  the  National  Lead  Com- 
pany. A  site  was  secured  at  Perth  Amboy,  N.  J.,  and  the 
construction  of  the  largest  white  lead  plant  in  the  world 
was  begun.  This  plant  was  to  have  a  producing  capacity 
of  20,000  tons  yearly,  and  it  was  rumored  that  as  soon  as 
completed  it  was  to  be  followed  by  the  erection  of  an 
equally  large  plant  in  East  St.  Louis,  for  which  the  site  had 
already  been  secured,  and  subsequently  by  another  plant  in 
Chicago.  This  policy  if  carried  out  would  have  resulted  in 
an  overproduction  of  white  lead,  as  the  National  Lead  Com- 
pany was  not  then  operating  all  of  its  plants,  and  this 
naturally  would  have  led  to  a  bitter  competitive  warfare 
for  the  supremacy  of  the  white  lead  markets. 

47.   Acquisition  of   the  United   Lead    Company.   Appar- 
ently the  National  Lead  Company  did  not  care  to  enter 


j- 

MfHk 

FIG.  5.  —  WHITE  LEAD  WORKS.  —  HAMMAR  BROTHERS. 

into  the  struggle,  as  even  before  the  Perth  Amboy  plant 
was  entirely  completed  they  acquired  control  of  all  of  the 
properties  of  the  United  Lead  Company,  the  sale  taking 
place  March  8,  1906.  This  substantially  gave  the  National 
Lead  Company  control  of  approximately  eighty  per  cent 
of  the  white  lead  manufactured  in  this  county  and  it  has 


DEVELOPMENT   OF  WHITE  LEAD    INDUSTRY.  3l 

been  strongly  intimated  that  the  National  Lead  Company 
shortly  afterwards  obtained  a  large  or  controlling  inter- 
est in  the  Carter  Company,1  the  independent  concerns 
being  represented  by  the  Matheson  Lead  Company, 
Wetherill  &  Sons,  Harrison  Brothers,  the  Eagle  White 
Lead  Company,  which  had  developed  a  capacity  of  over 
twelve  thousand  tons,  the  Hammer  White  Lead  Com- 
pany of  about  five  thousand  tons,  the  Pioneer,  and  the 
Rowley,  now  known  as  the  Mild  Process  Company,  which 
has  recently  built  a  new  five  thousand  ton  plant.  These 
companies  represented  at  that  time  an  aggregate  capacity 
of  about  thirty  thousand  tons  of  white  lead  and  oxides. 

48.  The  following  is  a  list  of  the  white  lead  plants  in 
the  United  States  with  their  locations  and  estimated 
capacities.  Those  not  in  operation,  as  near  as  the  writer 
can  learn,  are  indicated  by  leaving  the  capacity  blank. 
The  completion  of  the  Perth  Amboy  plant  in  1907  has 
doubtless  resulted  in  the  closing  down  of  some  of  the 
more  antiquated  plants  and  probably  in  reducing  the  pro- 
duction of  several  others,  as  the  total  estimated  tonnage 
capacity  is  considerably  in  excees  of  the  amount  of  white 
lead  produced.  These  figures  cannot  be  regarded  as  exact 
and  can  be  only  considered  estimates,  as  definite  informa- 
tion along  these  lines  is  very  difficult  to  secure. 
1  See  Mineral  Industry,  1906,  page  520. 


32 


THE  LEAD   AND   ZINC  PIGMENTS. 


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DEVELOPMENT   OF   WHITE   LEAD   INDUSTRY.         33 


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CHAPTER  IV. 

BRANDS,  PRODUCTION,  AND    PRICES  OF  WHITE  LEAD. 

49.  Brands.   The  following  arc  facsimiles  (pages  36  and 
37),  of  the  chief  brands  of  white  lead  offered  for  sale  by  the 
National  Lead  Company,  which  are  now  being  somewhat 
unified  by  the  use  of  the  accompanying  "  Dutch  Boy  "  label. 
Many  of  these  brands  have  a  national  reputation,  others 
have  attained  their  greatest  reputation  in  certain  locali- 
ties because  of  supposedly  distinct  qualities  and  properties 
possessed  by  them.     In  other  words,  each  brand  originally 
had  a  distinctive  and  individual  significance  to  the  master 
painter  using  it.     Now,  however,  as  these  brands  are  con- 
trolled by  a  single  corporation,  there  is  in  the  opinion  of 
many  no  satisfactory  assurance  that  they  are  any  longer 
made  in  the  same  plants  as  originally.     In  fact  the  writer 
understands  that  certain  brands  of  white  lead  each  bearing 
the  name  of  the  original  manufacturing  company  and  its 
location  are  still  being  offered  for  sale  when  as  a  matter  of 
fact  the  plants  of  these  former  companies  have  been  either 
abandoned  or  dismantled.     The  author  does  not,  however, 
wish  to  be  understood  as  stating  that  the  lead  offered  under 
these  brands  possesses  less  merit  than  formerly. 

50.  Short-weight  Packages.     The  adulteration  of  white 
lead  was  exceedingly  widespread  and  attained  its  greatest 
prevalence  prior  to  the  Civil  War.     The  establishment  of 
several  large  plants  shortly  after  the  close  of  the  war  gave 
a  decided  impetus  to  the  production  and  sale  of  strictly 
pure    white    lead.     This    movement    has    been    steadily 
growing  ever  since,  and  at  the  present  time  the  writer  does 
not  know  of  a  company  whose  business  is  strictly  the  manu- 

34 


BRANDS,  PRODUCTION,  AND  PRICES  OF  WHITE  LEAD.     35 


facture  of  white  lead  that  offers  for  sale  any  white  lead 
but  what  is  strictly  free  from  adulteration.  It  has,  how- 
ever, been  practically  a  universal  custom  for  many  years 
to  offer  white  lead  for  sale  in  short-weight  packages,  that 
is,  a  50 -pound  keg  of  lead  weighing  50  pounds  gross  weight 
instead  of  50  pounds  net.  In  a  number  of  actual  determi- 
nations made  by  the  writer  in  1900  the  following  shortage 
in  weights  was  observed: 


Number. 

Assumed  weight. 

Net 

weight. 

Shortage. 

Lbs. 

Lbs. 

Oz. 

Lbs.              Oz. 

I 

50 

46 

3 

4                   0 

II 

12* 

11 

13 

0                  11 

III 

12* 

10 

6 

2                    2 

IV 

12* 

10 

7 

2                   1 

V 

25 

21 

12 

3                   4 

VI 

25 

22 

7 

2                   9 

VII 

12* 

10 

0 

2                  8 

VIII 

12* 

11 

0 

1                  8 

Since  the  passage  of  laws  in  several  states  regulating  the 
sale  of  paints  and  paint  products,  which  require  net  weights 
and  measures  to  be  stated  on  the  label,  all  or  nearly  all  of 
the  corroders  are  offering  their  leads  in  full-weight  packages. 

51.  Annual  Production  of  White  Lead.  Annual  produc- 
tion of  white  lead  in  the  United  States,1  1884  to  1907. 


Year. 

Quantity. 

Value. 

Year. 

Quantity. 

Value. 

Short  tons. 

Dollars. 

Short  tons. 

Dollars. 

1884 

65,000 

6,500.000 

1896 

88,608 

8,371,588 

1885 

60,000 

6,300,000 

1897 

95,658 

9,676,815 

1886 

60.000 

7,200,000 

1898 

96,048 

9,400,622 

1887 

70,000 

7,560,000 

1899 

110,197 

11,317,957 

1888 

84,000 

10,080,000 

1900 

98,210 

10,657,956 

1889 

80,000 

9,600,000 

1901 

100,787 

11,252,653 

1890 

77,636 

9,382,967 

1902 

114,658 

11,978,174 

1891 

78,018 

10,454,029 

1903 

113,886 

12,837,647 

1892 

74,485 

8,733,620 

1904 

117,292 

13,026,954 

1893 

72,172 

7,695,130 

1905 

136,676 

15,738,649 

1894 

76,343 

6,662,307 

1906 

132,081 

16,929,250 

1895 

90,513 

8,723,632 

1907 

127,251 

16,448,324 

>  Mineral  Resources  of  United  States,  1884-1907. 


36 


THE    LEAD   AND  ZINC   PIGMENTS. 


R.LI,NG 

ITE  LEAD 

COHPASt 


•— ^  —  -i  —- 

FIG.  6.  —  FACSIMILES  OF  LEADING  BRANDS  OF  NATIONAL  LEAD 
COMPANY. 


BRANDS,  PRODUCTION,  AND  PRICES  OF  WHITE  LEAD.      37 


FIG.  7.— FACSIMILES  OF  LEADING  BRANDS  OF  NATIONAL  LEAD 
COMPANY. 


38 


THE   LEAD   AND    ZINC   PIGMENTS. 


52.  Sale  of  Dry  White  Lead.  White  lead  is  sold  by  the 
manufacturers  to  the  wholesale  and  retail  trade  ground  in 
about  eight  per  cent  of  linseed  oil  or  in  dry  form  to  the 
mixed  paint  manufacturers  for  use  in  prepared  paints. 
In  order  that  the  reader  may  gain  an  idea  of  the  increase 
in  the  sale  of  prepared  or  mixed  paints  and  its  effect  upon 
the  sale  of  white  lead  in  oil  the  following  figures  are  given, 
being  taken  from  the  United  States  Geological  Records. 
These  figures  also  serve  to  show  the  influence  of  paint 
legislation  and  public  agitation  along  these  lines.  The 
effect  has  not  been  particularly  noticeable  in  the  sale  of 
mixed  or  prepared  paints  but  rather  in  the  sale  of  reduced 
or  combination  white  lead,  as  at  the  present  date  (1908) 
the  writer  knowrs  of  several  large  paint  manufacturers 
whose  sales  of  combination  white  lead  have  fallen  off 
nearly  seventy-five  per  cent.  It  is  possible,  however, 
that  other  influences  have  contributed  to  produce  these 
results  in  part. 


Year. 

White  lead  in  oil. 

Dry  white  lead. 

Tons. 

Tons. 

1895 

76,000 

15,000 

1903 

62,674 

51,212 

1904 

58,332 

65,014 

1905 

62,767 

73,909 

1906 

93,763 

38,318 

1907 

92,216 

35,035 

53.  Differential  between  Pig  Lead  and  White  Lead. 
The  following  table  showing  the  variations  in  price  between 
pig  lead  and  white  lead  will  be  of  interest. 


BRANDS,  PRODUCTION,  AND  PRICES  OF  WHITE  LEAD.      39 


RANGE  OF  PRICES  PER  HUNDRED  POUNDS  OF  PIG  LEAD 
AND   WHITE  LEAD.1 


Year. 

Pig  lead. 

Dry  white  lead. 

White  lead  in  oil. 

1783 

9  50 

12  50 

1784 
1785 

9.82 
11   90 

11.90 
11  67 

1786 
1787 
1788 
1789 
1790 
1791 
1792 
1793 
1794 
1795 

9.92 
9.82 
9.82 
10.27 
9.82 
9.82 
9.82 
9.82 
10.71 
11  90 

11.43 
11.43 
11.10 

11.10 
10.71 
10.71 
10.96 
11.16 
13.84 
13  39 

1796 

11.16 

12.86 

1797 

11.30 

13.32 

1798 

11  90 

11  68 

1799 

12.50 

14.29 

1800 

12  50 

14  29 

1801 

14  29 

14  29 

1802 

12  50 

13  39 

1803 

12  50 

14  29 

1804 

13  98 

14  88 

1805 
1806 

13.98 

13   '.IS 
14  73 

15.00 
16  27 

1807 

16  74 

16  91 

1808 

16  96 

17  32 

1809 

16  29 

17  28 

1810 

14  29 

16  97 

1811 

14  29 

16  97 

1812 
1813 

11.16 

17.86 
21  43 

21.43 
24  12 

1814 

20  54 

21  88 

1815 
1816 

17.86 

21.43-35.71 
10  71 

21.43-35.71 
14  29 

1817 

10  71 

13  39 

1818 

10  71 

12  50 

1819 
1820 
1821 
1822 
1823 
1824 
1825 
1826 
1827 

6.70 
6.36 
6.63 
6.35 
5.36 
6.39 
7.59 
6.75 
6.14 

11.61 
11.61 
10.71 
10.71 
10.71 
10.71 
10.71 
10.71 
10.27 

12.50 
12.50 
12.50 
12.50 
12.50 
11.61 
11.61 
11.61 
11.61 

Mineral  Industry,  1894,  p.  408.     Mineral  Resources,  1894-1907, 


40 


THE  LEAD   AND   ZINC  PIGMENTS. 
RANGE  OF   PRICES.  — Continued. 


Year. 

Pig  lead. 

Dry  white  lead. 

White  lead  in  oil. 

1828 

5.39 

9.82 

11.61 

1829 

3.75 

7.59 

9.49 

1830 

3.75 

7.37 

8.60 

1831 

4.56-6.00 

8.24-8.73 

9.21 

1832 

5.94 

9.50 

10.66 

1833 

5.91 

9.50 

10.66 

1834 

5.13 

9.35 

10.16 

1835 

6.50 

9.86 

10.84 

1836 

6.38 

10.00 

11.50 

1837 

5.96 

11.12 

12.00 

1838 

5.29 

10.75 

11.50 

1839 

5.83 

10.25 

11.00 

1840 

4.89 

9.75 

10.25 

1841 

4.50 

9.00 

9.25 

1842 

3.81 

8.00 

8.25 

1843 

3.58 

7.75 

8.25 

1844 

3.90 

7.25 

8.25 

1845 

4.03 

7.50 

8.00 

1846 

4.73 

7.00 

8.00 

1847 

4.37 

6.90 

7.20 

1848 

4.26 

6.18 

6.83 

1849 

4.78 

7.31 

7.45 

1850 

4.80 

7.00 

7.22 

1851 

4.85 

6.75 

7.28 

1852 

4.80 

6.31 

7.06 

1853 

6.45 

8.75 

9.50 

1854 

6.57 

8.50 

9.25 

1855 

6.87 

8.75 

9.02 

1856 

6.59 

8.37 

9.09 

1857 

6.18 

8.25 

9.00 

1858 

5.94 

8.50 

8.77 

1859 

5.50 

7.25 

8.00 

1860 

5.65 

7.25 

8.00 

1861 

5.25 

7.27 

8.07 

1862 

6.10 

8.20 

8.47 

1863 

6.25 

10.44 

12.17 

1864 

7.10 

16.72 

16.81 

1865 

6.60 

15.58 

15.88 

1866 

6.90 

13.41 

16.13 

1867 

6.50 

12.73 

14.34 

1868 

6.50 

12.19 

13.60 

1869 

6.45 

13.27 

12.00 

1870 

6.25 

9.64 

10.85 

1871 

6.10 

9.68 

11.30 

1872 

6.35 

9.41 

11.33 

1873 

9.30 

10.62 

11.83 

1874 

6.00 

10.50 

11.25 

1875 

5.95 

10.00 

10.84 

1876 

6.05 

10.00 

10.50 

BRANDS,  PRODUCTION,  AND  PRICES  OF  WHITE  LEAD.     41 
RANGE  OF   PRICES.  —  Continued. 


Year. 

Pig  lead. 

Dry  white  lead. 

White  lead  in  oil. 

1877 

5.45 

9.30 

9.81 

1878 

3.60 

7.50 

8.08 

1879 

4.18 

7.00 

7.46 

1880 

5.06 

8.00 

8.54 

1881 

4.89 

6.58 

7.03 

1882 

4.91 

6.17 

6.67 

1883 

4.32 

6.18 

6.68 

1884 

3.74 

5.50 

6.00 

1885 

3.95 

4.98 

5.48 

1886 

4.63 

4.88 

5.38 

1887 

4.50 

5.87 

6.37 

1888 

4.42 

5.16 

5.66 

1889 

3.93 

4.89 

5.39 

1890 

4.48 

5.43 

5.93 

1891 

4.35 

5.80 

6.30 

1892 

4.05 

6.50 

6.75 

1893 

3.69 

5.75 

6.38 

1894 

3.29 

4.50 

5.26 

1895 

3.23 

4.25 

5.00 

1896 

3.03 

4.38 

4.90 

1897 

3.64 

4.63 

5.00 

1898 

3.79 

4.50 

5.08 

1899 

4.53 

5.00 

5.35 

1900 

4.55 

5.07 

5.57 

1901 

4.21 

5.39 

5.87 

1902 

4.21 

5.09 

5.62 

1903 

4.23 

5.25 

6.12 

1904 

4.42 

5.13 

6.12 

1905 

5.28 

6.25 

6.50 

1906 

5.83 

6.32 

6.86 

CHAPTER  V. 

THE  MODERN  APPLICATION   OF  THE  DUTCH  PROCESS 
IN  THE  UNITED   STATES. 

54.  Present  Importance  of  the  Dutch  Process.     By  far 

the  larger  proportion  of  white  lead  manufactured  to-day 
is  still  made  by  the  old  Dutch  process,  so  called,  and  while 
some  of  the  newer  processes  have  been  very  successful  in 
their  operation,  producing  high  grades  of  white  lead  at  a 
cost  not  exceeding  that  of  old  Dutch  process  white  lead, 
and  one  or  two  of  them  at  a  very  much  less  figure,  yet  by 
reason  of  the  fact  that  it  has  meant  the  introduction  of 
new  brands  on  the  market,  competing  against  well-known 
brands  of  long  standing,  the  development  and  expansion 
of  these  newer  processes  has  been  slow,  but  at  the  same 
time  more  or  less  sure,  and  it  is  more  than  probable  that 
within  a  very  few  years  they  will -constitute  as  important 
factors  in  the  white  lead  industry  as  the  Solvay  and  elec- 
trolytic processes  have  in  the  soda  industry. 

55.  Processes  in  Use.     Confining  our  discussion  at  the 
present  time  to  the  white  lead  industry  of  the  United  States 
and   neglecting   the   large   number   of   experimental   and 
patented  processes  that  for  one  reason  or  another  have  not 
proven  successful  in  actual  commercial  practice,  the  follow- 
ing may  be  considered  as  the  processes  by  which  white  lead 
is  made  in  this  country  at  the  present  time : 

1.  Old  Dutch  process. 

2.  Carter  process. 


3.  Matheson  process. 

4.  The  Mild  process  (Rowley) 

42 


MODERN  APPLICATION   OF   THE  DUTCH   PROCESS.        43 


44  THE   LEAD   AND   ZINC  PIGMENTS. 

Several  electrolytic  processes  have  been  devised,  but  the 
writer  is  not  aware  that  they  have  yet  been  developed  on  a 
successful  commercial  scale. 

As  conducted  in  this  country  at  the  present  time  the  old 
Dutch  process  is  substantially  as  follows : 

56.  Grade  of  Pig  Lead  Required.  The  pig  lead  used  must 
be  a  double  refined  lead,  which  usually  commands  a  price  at 
least  ten  cents  above  the  best  grades  of  ordinary  'refined 
lead.  The  following  analysis  is  typical  of  a  good  grade  of 
corroding  lead : 

Constituents.  Per  cent. 

Silver 0.0006 

Arsenic 0 .0050 

Antimony trace 

Tin 0.0003 

Copper .. none 

Bismuth 0.0100 

Iron 0.0015 

Zinc trace 

Manganese < .       none 

Nickel  and  cobalt none 

Impurities 0 . 0174 

Lead  by  difference 99.9826 


100.0000 

The  commercial  impurity  which  is  the  cause  of  the  greatest 
trouble  is  bismuth,  a  lead  becoming  "  common  "  when  it 
contains  as  much  as  0.0800  per  cent  of  bismuth. 

57.  Casting  the  Buckles.  The  pig  lead  is  melted  in  a 
large  iron  kettle  and  allowed  to  flow  continuously  on  to  an 
endless  double  belt  of  molds,  which  form  the  lead  into 
perforated  disks  of  about  one  pound  each,  these  disks  being 
commonly  known  as  buckles,  due  to  the  fanciful  resem- 
blance to  the  large  metallic  buckles  used  as  ornaments  on 


MODERN  APPLICATION   OF   THE   DUTCH  PROCESS.      45 


I' 


46  THE  LEAD   AND   ZINC  PIGMENTS. 

shoes  in  the  earlier  times.  It  is  absolutely  necessary  that 
these  buckles  be  cast,  as  a  rolling  process  would  harden  or 
change  the  crystalline  nature  of  the  lead  to  such  an  extent 
that  it  would  be  impossible  to  corrode  it.  It  is  therefore 
extremely  necessary  that  all  the  parts  of  the  casting  sys- 
tem must  work  in  entire  harmony  —  the  temperature  of 
the  molten  lead,  the  speed  with  which  the  chain  of  molds 
travels,  and  length  of  the  mold  belt  —  in  order  to  secure 
the  best  results.  A  double  line  of  molds  will  cast  about 
eighty  buckles  per  minute.  The  heat  of  the  molds  and  the 
temperature  at  which  the  lead  is  run  upon  them  has  a  very 
decided  influence  upon  the  ease  of  corrosion.  The  buckles 
are  conveyed,  generally  by  wheelbarrows,  to  the  corroding 
houses,  which  are  compartments  square  or  nearly  so, 
twenty  or  twenty-five  feet  each  way,  located  in  a  large 
building  or  shed  usually  one  story  in  height. 

58.  Building  the  Stack.  Usually  sixteen  to  eighteen 
buckles  are  placed  in  each  corroding  pot,  about  one  pint  of 
commercial,  number  eight  acetic  acid,  diluted  to  three  per 
cent  of  true  acetic  acid,  having  been  placed  in  the  well  of 
the  pot.  The  pots  are  strongly  built  of  earthenware,  the 
only  glazed  portion  being  the  well.  The  loaded  pots  are 
then  placed  side  by  side  on  a  layer  of  tan -bark  and  horse 
manure  about  two  and  one-half  feet  in  depth,  and  an  outer 
layer  about  one  foot  in  breadth  between  the  walls  of  the 
stack  and  the  pots.  About  one- third  fresh  tan -bark  is 
used  each  time,  the  other  two-thirds  being  that  used  in  the 
previous  corrosion,  sixty  to  seventy  bushels  of  manure  being 
used  to  about  seven  hundred  bushels  of  tan-bark.  The 
tan -bark  used  is  that  obtained  from  tanneries,  and  in  the 
most  modern  Dutch  process  plants  it  is  conveyed  from 
the  yard  to  the  stack  by  means  of  electric  cranes  or  carriers. 
The  layer  of  pots  is  then  covered  over  with  a  double  layer  of 
boards  on  which  is  placed  more  tan-bark,  the  upper  layers 


MODERN  APPLICATION  OF  THE  EUTCH  PROCESS.     47 

usually  being  about  one  foot  in  depth.  More  pots  are 
placed  on  the  tan-bark,  and  in  this  manner  the  "  stack  " 
so  called  is  built  up  layer  after  layer,  and  when  finished 
is  usually  ten  or  twelve  layers  high,  and  contains  from  sixty 
to  one  hundred  and  twenty  tons  of  lead,  one  hundred  tons 
probably  being  a  fair  average.  This  operation  requires 
the  services  of  four  men  for  about  three  days.  Each  layer 
of  pots  is  connected  by  a  flue  or  vent  leading  to  the  roof, 


FIG.  10.  —  ELKCTRIC  CRANE  FOR  CONVEYING  TAN-!>ARK.  —  HAMMAR  BROS. 


which  permits  the  gares  due  to  the  decomposition  of  the 
moistened  mixture  of  tan-bark  and  manure  to  escape.  The 
temperature  and  smell  of  the  escaping  gases  and  steam 
and  their  apparent  volume  furnish  the  cnly  means  of  judg- 
ing the  conditions  inside  of  the  stack  and  progress  of  the 
corrosion,  and  also  the  only  possible  means  of  regulating 
these  conditions  by  closing  or  partially  closing  the  flues, 
thus  controlling  to  some  extent  the  reactions  imdile.  the 
stack.  The  temperature  if  too  low  will  check  the  corro- 


THE  LEAD   AND   ZINC  PIGMENTS. 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.       49 

sion  or  retard  it  entirely ;  if  too  high  will  cause  the  forma- 
tion of  a  crystalline  or  sandy  white  lead  or  even  a  yellow 
product  which  is  largely  oxide. 

59.  Reactions  Involved  in  the  Corrosion.   The  stacks  are 
allowed  to  remain  undisturbed  for  one  hundred  to  one 
hundred  and  twenty  days.    The  tan-bark  and  manure,  hav- 
ing been  carefully  tempered  prior  to  their  introduction  into 
the  stack,  rapidly  ferment,  the  temperature  rising  rapidly 
to  160  to  175°  F.,  a  temperature  sufficient  to  vaporize  the 
acetic  acid  and  the  moisture  in  the  tan-bark.     The  mixed 
vapors  attack  the  metallic  lead,  forming  first  a  basic  lead 
acetate.     A  large  amount  of  carbon  dioxide  is  also  liber- 
ated during  the  fermentation,  which  reacts  with  the  basic 
acetate,  forming  a  basic  lead  carbonate,  or  what  is  com- 
monly known  as  white  lead.     The  transformation  of  the 
lead  may  be  represented  by  the  following  equations: 

1.  Pb  +  2C2H402  =  H2  +  Pb(C2H3O2)2. 

2.  3  Pb(C2H302)2  +  2  H2O  =  2  Pb(C2H3O2)2 .  Pb(OH)2 

+  2C2H402. 

3.  2  Pb(C2H302)2  •  Pb(OH)2  +  2  C02-f  2  H2O 

=  2  PbC03  •  Pb(OH)2+4  C2H402. 

Several  authorities  consider  the  liberation  of  hydrogen 
as  improbable  and  believe  the  reactions  proceed  as  follows : 

1.  Pb+H20  +  0  =  Pb(OH)2. 

2.  Pb(OH)2+2  C2H402  =  Pb(C2H302)2  +  2  H20. 

3.  Pb(C2H302)2  +  2  Pb(OH)2  =  Pb(C2H302)2  -  2  Pb(OH)2. 

4.  3  [Pb(C2H302)2  •  2  Pb(OH)2]+4  C02  =  3  Pb(C2H302)2 

+2  [Pb(OH)2  •  2  PbCOj  +4  H2O. 

60.  These  reactions  indicate  that  the  acetic  acid  or  the 
neutral  lead  acetate  is  continually  regenerated,  attacking 
more  of  the  metallic  lead,  and  the  reaction  becoming  cyclic 
until  the  larger  portion  of  the  lead  is  converted  into  white 


50 


THE   LEAD   AND    ZINC   PIGMENTS. 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.        51 

lead,  the  operation  becoming  slower  and  slower  as  the 
crust  or  coating  of  white  lead  on  the  metal  increases  in 
thickness,  usually  coming  to  a  standstill  when  70  to  80 
per  cent  of  the  metal  has  become  converted.  The  horse 
dung  acts  as  the  starter  for  the  tan-bark,  causing  the  fer- 
mentation to  begin  more  quickly  and  proceed  more  rapidly 
in  the  initial  stages.  If  it  were  not  for  the  discoloration 
of  the  white  lead,  due  to  the  action  of  hydrogen  sulphide 
and  other  sulphur  compounds,  the  horce  dung  would  be 
used  in  much  larger  quantities,  as  its  action  is  very  much 
more  rapid  and  complete  than  that  of  the  tan-bark. 

61.    Conditions  Required  for  Successful  Corrosion.    The 


FIG.  13.  —  COMPLETED  STACK.  —  HAMMAR  BROTHERS. 

correct  tempering  of  the  tan -bark  is  the  most  important 
part  of  the  process.  If  an  excessive  amount  of  water  is 
used,  or  the  water  is  too  hot,  or  the  heap  of  bark  allowed 
to  overheat,  the  tan  will  be  "  killed/'  as  it  is  termed,  i.e., 


52 


THE   LEAD   AND   ZINC  PIGMENTS. 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.       53 

the  principle  which  causes  the  fermentation  is  checked. 
Whether  this  principle  is  a  form  of  bacteria  or  an  enzyme 
is  not  definitely  known,  but  on  its  proper  cultivation 
depends  the  success  of  the  corrosion. 

62.  Taking  Down  the  Stack.   At  the  expiration  of  the 
allotted  time  the  stack  is  taken  down  in  the  same  manner 
as  erected,  except  of  course  the  operations  are  reversed. 
A  considerable  number  of  the  pots  will  be  found  to  be 
broken,  due  to  the  weight  of  the  stack.     As  long,  how- 
ever, as  the  well  of  the  pot  remains  intact  it  can  be  used  to 
advantage,  because  in  such  instances  the  corrosion  is  more 
nearly  complete,  as  the  gases  and  vapors  have  freer  access 
to  the  buckles.     The  buckles,  if  the  corrosion  has  been 
conducted  properly,  will  be  found  to  have  become  changed 
into  a  white  hard  porcelain-like  mass  of  the  same  general 
shape  as  the  original  buckle  but  warped  and  swollen  and 
usually  containing  a  portion  of  uncorroded  lead  in  the  center. 
The  completeness  of  the  corrosion  will  vary  not  only  with 
different  stacks  but  in  different  portions  of  the  same  stack. 

63.  Very  slight  amounts  of  impurities  such  as  bismuth, 
antimony,  arsenic,  and  zinc  will  retard  the  conversion  or  cor- 
rosion very  seriously.     Great  care  must  also  be  exercised  in 
the  moistening  and  tempering  of  the  tan-bark.     Improper 
tempering  may  cause  the  stack  to'"  die, "resulting  in  a  very 
low  percentage  of  corrosion.     Occasionally  the  fermenta- 
tion of  the  tan-bark  may  be  so  rapid  as  to  dehydrate  the 
white  lead  as  fast  as  formed  into  a  yellow  oxide.     With 
due  care  these  undesirable  results  may  be  avoided,  but 
there  are  other  less  troublesome  results  arising  from  obscure 
conditions  which  cannot  be  readily  controlled,  such  as  soft 
and  fluffy  corrosions  which  require  more  oil  in  grinding 
and  have  less  hiding  power. 

64.  Sandy  Lead.   If  the  pig  lead  or  the  stack  conditions 
have  not  been  suitable  the  buckles  on  being  broken  will 


54 


"THE   LEAD   AND   ZINC  PIGMENTS. 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.        55 

show  a  grainy,  glistening,  crystalline  structure  due  to 
crystals  of  neutral  lead  carbonate.  This  results  in  a  white 
lead  of  diminished  hiding  power  which  is  very  difficult  to 
grind  and  settles  out  as  a  useless  sandy  lead  when  thinned 
down  to  painting  consistency. 

Notwithstanding  every  precaution  taken  by  an  experi- 
enced corroder,  a  variable  percentage  of  such  lead  will  be 
found  in  eveiy  corrosion. 

65.   The  labor  item  in  taking  down  the  stack  is  very 


FIG.  1G. — CRUSHING  ROLLS. 

nearly  equal  to  that  of  putting  it  up,  as  the  boards  have 
to  be  taken  up  carefully  in  order  to  avoid  getting  bits  of 
tan-bark  into  the  pots  of  corroded  lead,  and  either  con- 
veyed to  the  yard  or  placed  on  pegs  projecting  from  the 
wall.  The  tan-bark  is  wheeled  or  conveyed  to  the  yard; 
the  contents  of  the  pots  are  also  wheeled  to  the  crushing 
and  grinding  mill. 


CHAPTER  VI. 

THE  MODERN  APPLICATION  OF  THE  DUTCH  PROCESS 
IN  THE  UNITED   STATES  (Continued). 

66.  Disintegrating  the  Buckles.     In  order  to  separate 
the  crust  of  white  lead  from  the  metal  core  the  buckles  are 
crushed   between  large  steel  grooved  rollers  and   passed 
through  a  coarse  screen  which  retains  the  larger  pieces 
of  metallic  lead.     The  portion  passing  through  the  screen, 
which    still    contains    considerable  metallic    lead,   is    run 
through    the    flattening   rolls,  which  further  disintegrate 
the  corroded  lead  and  flatten  out  the  metallic  particles  so 
that  they  are  retained  on  a  finely  meshed  screen.     The 
white  lead  passing  through  is  ground  with  water  in  large 
stone   mills,   the  grinding  surfaces  of  which  have  to  be 
frequently  recut  and  dressed,  due  to  the  hardness  of  the 
white   lead   particles.     In   order  to   remove   the   metallic 
lead  which  often  clogs  the  mills  by  filling  the  grooves  in 
the  stone,  common  salt  is  often  put  in  the  hopper  in  con- 
siderable quantities. 

67.  Washing  the   Lead.     From  the   grinding  mills  the 
white  lead  is   conveyed  to  the  float  table  or  drag  box, 
where    the    coarser    and    more    crystalline    particles    are 
settled   out   to    be    reground.     The    lighter   particles   are 
floated  off  and  washed  thoroughly  in  a  series  of  agitator 
tubs  with  an  increased  amount  of  water  to  remove  as 
much    of   the  acetic  acid  and  the  more  or  less  insoluble 
basic  acetates  of  lead  as  possible,  the  purified  white  lead 
finally   passing  through  a  fine   silk  bolting  cloth   to   re- 
move any  particles  of  tan-bark  and  metallic  lead  remain- 
ing in  it. 

56 


MODERN  APPLICATION   OF  THE  DUTCH  PROCESS.       57 


.  17.  —  WATEK  GRINDING  MILLS.  —  HAMMAB  BROTHERS. 


58 


THE   LEAD   AND   ZINC  PIGMENTS. 


68.  Importance  of  Thorough  Washing.  The  washing  of 
the  white  lead  must  needs  be  thorough,  as  nearly  all  the 
acetic  acid  used  is  present  in  the  white  lead  buckles  when 
removed  from  the  corroding  pots,  as  solid  acetate  of  lead 
constituting  one-half  to  one  per  cent  of  the  weight  of  the 
buckle  and  if  not  properly  removed  seriously  affects  the 


FIG.  18.  —  DRAG  AND  WASHING  Box. 


service  value  of  the  white  lead.  An  eminent  paint  chemist 
in  discussing  this  matter  says  that  "  slight  traces  of  ace- 
tate in  the  ground  lead  in  oil  render  it  not  only  far 
more  readily  attacked  by  the  blackening  influence  of  the 
sulphur  fumes  and  sulphuretted  hydrogen  of  the  air,  but 
also  act  upon  the  linseed  oil  with  which  it  is  mixed,  so  that 
it  reaches  the  final  state  of  oxidation  and  perishes  much 
more  quickly  than  would  otherwise  be  the  case,  resulting 


UNIVERSITY 

OF 


MODERN  APPLICATION   OF  THE  DUTCH  PROCESS.        59 


60  THE   LEAD   AND   ZINC  PIGMENTS. 

in  the  rapid  chalking  of  the  lead.  Under  the  influence  of 
moisture  and  the  carbonic  acid  gas  of  the  air  complete 
corrosion  and  change  of  the  basic  carbonate  into  the  trans- 
parent crystalline  normal  carbonate  may  also  take  place 
when  acetate  of  lead  is  left  in  the  finished  product." 

69.  Drying   the    Lead.   After  having   been   pumped   to 
large  settling  tanks,  where  the  excess  of  water  is  drawn 
off,  the  white  lead  paste,  carrying  fifty  to  sixty  per  cent 
of  water,  is  pumped  on  to  large  copper  drying  pans  usually 
arranged  in  series  three  to  four  pans  high.     The  dimensions 
of  the  pans  will  vary  in  the  different  plants;  eight  feet  in 
width  by  about  sixty  feet  in  length  is  a  very  common  size. 
Each  pan  is  jacketed  and  so  constructed  as  to  withstand 
considerable  pressure,  the  steam  circulating  from  one  pan 
to  the  next  in  the  same  series. 

70.  The  paste  lead  is  usually  pumped  on  to  the  pans  to  a 
depth  of  about  six  inches,  and  as  soon  as  it  has  dried  to 
a  solid  consistency  it  is  marked  off  into  squares,  which 
ultimately   causes   the   formation   of   cracks   as   the   lead 
shrinks  and  thus  hastens  the  drying.     About  six  to  eight 
days  are  required  to  dry  the  pasty  mass  moisture  free. 
The  lead  is  removed  as  soon  as  thoroughly  dry,  as  over- 
drying  tends  to  the  formation  of  a  crust  which  is  hard  to 
grind.      It  is  then  taken  from  the  pan  with  the    aid  of 
wooden  shovels  and  packed  dry  in  barrels  by  means  of  a 
mechanical  barrel  packer  or  sent  to  the  mills  to  be  ground 
in  oil. 

71.  Loss  of  Lead  in  Washing.   The  large  volume  of  wash 
waters  used  in  this  process  entails  a  considerable  loss  of 
lead,  a  portion  of  which  is  recovered  by  the  more  careful 
corroders   by   precipitating  out   with   sodium   carbonate; 
even  with  this  precaution  and  the  use  of  large  settling 
tanks   a   considerable   amount   ultimately   finds   its   way 
annually  into  the  sewer. 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.       61 


62       •  . -:       THE  LEAD  AND  ZINC  PIGMENTS. 

72.  Effect  of  Sandy  Lead  in  Paints.   The  utility  of  white 
lead  for  certain  purposes  depends  quite  largely  on  the 
care  exercised  in  freeing  it  from  "  sandy  "  lead,  i.e.,  the 
dense,  hard  grains  of    crystalline  carbonate  due  to  over- 
corrosion  or  unequal  distribution  of  the  corroding  agencies. 
In  interior  brush  work  or  in  dipping  paints  where  the  white 
lead  is  thinned  with  a  considerable  amount  of  turpentine 
or  benzine  the  sandy  lead  will  rapidly  settle  out  as  a  useless 
sediment,  and  it  is  the  firm  belief  of  the  writer  that  the 
majority   of    old   Dutch    process   white    lead  would    be 
considerably  better  for  the  removal  of  at  least  three  to 
five  per  cent  of  crystalline  lead. 

73.  Cost  of  a  Stack  Operation.   The  following  figures  as 
to  cost  and  yields  are  believed  by  the  writer  to  be  fairly 
representative,  as  they  are  obtained  from  a  run  of  a  one- 
hundred -ton  stack  for  the  usual  corroding  period,  with 
average  conditions  and  prices.     These  figures  are  exclu- 
sive of  all  costs  and  expenses  outside  of  the  stack. 

Materials  composing  stack.  Cost. 

210,000  buckles  equivalent  to 
200,000  pounds  of  lead  at  $6  per 

hundredweight $12,000 . 00 

10,000  corroding  pots 600 . 00 

4,000  pounds  acetic  acid 80 . 00 

Lumber  (portable) 130.00 

100  cords  tan-bark 350.00 

Labor  setting  up  stack 40 . 00 

Labor  taking  down  stack 30 . 00 

Miscellaneous. .  20.00 


$13,250.00 


MODERN   APPLICATION  OF  THE  DUTCH  PROCESS.        63 


64  THE  LEAD   AND   ZINC  PIGMENTS. 

Products  obtained.  Value. 

178,000  pounds  white  lead  at  6  cents 

per  pound $10,680.  00 

50,000  pounds  uncorroded 3,000.00 

6,000  pounds  tailings 210.00 

Lumber  fit  to  reuse 120.00 

Pots  less  breakage 565 . 00 

Tan-bark,  two-thirds  to  be  used  over  233.00 


$14,808.00 

Increase  in  value $1,558.00 

Increase  in  product 
200,000  Ibs  lead  set 
50,000  Ibs.  lead  uncorroded 


150,000  Ibs.  lead  corroded  =  178,000  Ibs.  white  lead, 

6,000  Ibs.  tailings. 


184,000  Ibs.  total  yield. 
184,000  Ibs. 
150,000  Ibs. 


34,000  Ibs.  chemical  increase  =  22.7  per  cent. 
Theoretical  chemical  increase  =  24.8  per  cent. 

74.  It  should  be  stated  that  these  figures  were  obtained 
during  a.  year  in  which  there  was  practically  no  difference 
between  the  price  of   pig  lead    and   dry  white  lead,  this 
being  an  exceptional  occurrence,  as  there  is  generally  a 
marked  difference  between  the  two,  resulting  in  a  much 
greater  profit,  which  can  be  readily  calculated  by  inserting 
the  prevailing  market  values. 

75.  Economy  of  Process.   While  it  is  probable  that  labor- 
saving  devices  and  appliances  have  not  J>een  utilizedL  to  the 
greatest  extent  possible,  in  the  majority  of  old  Dutch  cor- 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.       65 


66  THE  LEAD   AND   ZINC  PIGMENTS. 

roding  plants,  the  nature  of  the  process  itself  is  not  con- 
ducive to  mechanical  economies.  Nevertheless  the  art  is 
much  more  advanced  in  this  country  with  respect  to  labor- 
saving  appliances  and  the  preservation  of  health  among 
the  workmen  than  in  Europe.  This  is  especially  true  with 
regard  to  the  washing  and  drying  of  the  white  lead. 

76.  Variation  in  Quality.   There  has  been  considerable 
controversy  during  the  past  few  years,  especially  among 
the  master  painters,  as  to  whether  the  old  Dutch  process 
white  lead  of  to-day  is  the  equal  of  that  produced  by  the 
same   process   in  less  recent  years.     In   this  country,  as 
explained  in  a  previous  chapter,  the  large  majority  of  the 
white  lead  plants  are  under  the  control  of  a  single  corpo- 
ration having  a  central  office  which  receives  the  regular 
routine  reports  of  the  various  factories  as  regards  labor, 
materials  used,  yields  and  details  of  process,  and  it  is  only 
natural  that  each  plant  would  endeavor  to  obtain  the 
greatest  percentage  of  corrosion  with  the  least  expense, 
and  with  a  process  which  admittedly  does  not  give  a  uni- 
form product  at  all  times,  it  is  easy  to  see  how  quality  may 
at  times  be  sacrificed  for  quantity.     It  was  formerly  the 
custom  of  the  most  careful  corroders  to  sort  and  separate 
out  the  imperfect  corrosions,  and  in  addition  age  their  lead 
by  storing  in  large  bins  for  a  considerable  length  of  time 
before  grinding  in  oil,  and  the  writer  understands  that  this 
custom  still  prevails  among  the  conservative  English  man- 
ufacturers to-day. 

77.  Lack  of  Proper  Grinding  of  White  Lead.   While  the 
practice  discussed  above  may  have  a  considerable  bearing 
on  the  question,  the  present-day  practice  of  grinding  white 
lead  by  the  manufacturers  of  this  country  has,  in  the 
opinion  of  the  writer,  very  much  more  to  do  with  the  ser- 
vice or  wearing  value  of    white  lead  than  most  investi- 
gators and  writers  have  been  led  to  believe.    The  writer 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.       67 

has  visited  several  of  the  largest  white  lead  plants  in  the 
country,  and  found  them  grinding  their  white  lead  in  oil  in 
a  double  set  of  stone  mills  which  were  not  water-cooled, 
with  the  obvious  result  that  as  the  day  progressed  the  mills 
became  hotter  and  hotter,  and  after  five  or  six  hours  of 
steady  running  the  lead  as  it  came  from  the  mills  averaged 
in  three  specific  cases  262°  F.,  280°  F.  and  284°  F.,  the  tem- 
peratures were  taken  by  the  writer  himself,  and  were  from 
different  mills  and  represented  two  different  factories. 
These  figures  have  been  repeatedly  verified  by  the  writer  in 
numerous  plants,  and  temperatures  as  high  as  300°  F.  have 
been  noted  at  the  close  of  the  day's  run,  and  yet  according 
to  the  records  of  the  operator  of  the  mill  no  temperature 
higher  than  125°  F.  was  recorded.  It  is  not  an  easy  matter 
to  ascertain  accurately  the  temperature  of  the  lead  just  as 
it  emerges  from  the  mill,  and  it  was  much  easier  for  the 
workman  to  take  the  temperature  of  the  lead  as  it  dropped 
into  the  keg,  some  little  distance  from  the  mill,  and  by  that 
time  the  lead  was  fairly  cool  and  his  figures  not  far  from 
correct.  This  practice  of  grinding  hot  lead  is  much  more 
general,  the  writer  believes,  than  most  paint  authorities 
imagine. 

78.  Changes  that  may  take  place  in  Grinding.  Two  of 
the  most  powerful  aids  in  producing  a  chemical  reaction  or 
combination,  where  the  tendency  of  the  substances  to  com- 
bine is  not  pronounced,  are  heat  and  pressure,  and  in  a  large, 
uncooled  white  lead  mill  running  steadily  for  ten  hours,  the 
above-mentioned  conditions  are  certainly  attained  to  a 
high  degree,  and  a  more  or  less  pronounced  combination 
of  white  lead  and  linseed  oil  must  inevitably  take  place 
with  the  formation  of  a  lead  soap,  possibly  accompanied 
by  further  structural  changes  in  the  white  lead  molecule. 
This,  in  the  opinion  of  the  writer,  is  the  reason  why  much 
of  the  white  lead  manufactured  in  this  country  chalks 


68 


THE   LEAD   AND    ZINC   PIGMENTS. 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.       69 

more  readily  and  does  not  possess  the  wearing  qualities  of 
the  more  carefully  ground  English  leads.  One  of  the  fore- 
most authorities  on  the  manufacture  of  white  lead,  in  a 
letter  to  the  writer,  confirms  this  view  with  the  following 
statement :  "  I  do  not  feel  that  it  is  safe  to  heat  white  lead 
over  150°  F., —  preferably  not  over  125°  F.,  as,  if  it  is 
heated  above  the  higher  temperature,  saponification  is  apt 
to  ensue,  with  toughening  of  the  mixture,  discoloration 
and  actual  change  in  the  nature  of  the  material." 

79.  English  Methods  of  Grinding.  The  method  still 
followed  by  the  more  conservative  English  manufacturers 
of  using  roller  mills  for  incorporating  the  lead  with  oil  has 
much  to  commend  it  in  avoiding  these  difficulties.  A  lead- 
ing English  authority,  in  discussing  this  subject  with  the 
writer,  stated  that  "  many  of  our  large  English  firms  have 
tried  the  American  water-cooled  mills,  but  with  very  dis- 
appointing results.  Two  London  firms,  in  <  particular, 
installed  six  of  these  mills,  but  have  thrown  them  out 
and  are  using  the  English  combination  roller  mills."  The 
writer  believes  that  the  cooling  effect  of  the  water-cooled 
mill  has  been  overrated,  as  the  stones  are  sueh.  exceed- 
ingly poor  conductors  of  heat  that  the  grinding  face  of 
the  stone  may  be  exceedingly  hot,  and  yet  the  other  sur- 
face which  is  in  contact  with  the  water  may  be  compara- 
tively cool;  in  other  words,  the  cooling  effect  of  the  water  is 
really  very  slight,  unless  there  is,  as  often  is  the  case,  a  ten- 
dency for  the  mill  to  heat  up  very  hot,  260  to  300°  F.,  in 
which  case  the  water  will  exert  a  considerable  cooling  effect, 
but  with  temperatures  around  200°  F.  and  below,  the  cool- 
ing effect  is  almost  negligible,  especially  during  the  sum- 
mer months.  The  degree  of  heating  will  of  course  depend 
on  how  "  tight"  the  mill  is  set.  The  writer  has  repeatedly 
observed  temperatures  as  high  as  255°  F.  in  the  most 
approved  types  of  water-cooled  mills,  when  a  "  close  grind  " 


70 


THE  LEAD  AND   ZINC  PIGMENTS. 


MODERN  APPLICATION  OF  THE  DUTCH   PROCESS.        71 

was  required,  and  that,  too,  as  early  as  two  o'clock  in  the 
afternoon. 

80.  Combination  Leads.   Neither  are  the  manufacturers 
of    combination   white   leads,    so-called,    always    exempt 
from  the  above  criticisms,  and  many  of  the  ills  ascribed  to 
the  use  of  combination  leads,  such  as  hardening  in  the 
keg,  are  more  often  due  to  the  practice  of  grinding  in  hot 
mills  than  to  the  inert  materials  employed,  although  some 
inert  pigments,  notably  silica,  tend  materially  to  aggravate 
the  heating  of  the  mill. 

81.  The  English  mills  have  a  much  greater  capacity 
than  is  conceded  them  by  the  advocates  of  the  American 
system  of  grinding.     The  type  of  mill  illustrated  in  this 
connection,  having  a  7-foot  chasing  pan  and  fitted  with 
33-inch  by  16-inch  tandem  triple  granite  rolls  is  capable  of 
turning  out  from  8  to  10  tons  of  white  lead  per  day,  while 
a  40-inch  American  mill  will  seldom  exceed  3  tons. 

82.  Pulp  Ground  Lead.   Another  means  of  incorporat- 
ing white  lead  with  oil  has  come  into  use  during  the  last 
fifteen  or  twenty  years  and  affords  a  product  which  has 
obtained  much  favor  in  the  Eastern  section  of  the  country. 
The  writer  refers  now  to  "  pulp  "  ground  lead.     In  this 
process  the  paste  of  lead  and  water  which  would  other- 
wise be  pumped  onto  the  dry  pan  is  pumped  into  a  care- 
fully  measured   and   weighed   box  placed   on  stationary 
scales,  and  the  actual  weight  of  white  lead  present  in  the 
paste  determined,  the   correct   amount  of  oil  added  and 
the  contents  of  the  box  dumped  into  a  tall,  very  narrow 
upright  mixer.     Owing  to  the  greater  affinity  of  the  oil 
for  the  lead  a  continuous  separation  of  water  takes  place, 
which  rises  to  the  top,  while  the  stiff  paste  of  lead  and  oil 
works  to  the  bottom  and  is  carried  off  by  a  screw  conveyor 
either  to  a  grinding  mill  or  is  filled  directly  into  the  kegs. 
If  the  latter,  the  percentage  of  water  will  usually  be  over 


72  THE   LEAD   AND   ZINC   PIGMENTS. 

0.5  per  cent,  while  if  it  has  been  ground  in  a  mill,  sufficient 
heat  is  usually  generated  to  bring  the  water  content  below 
0.5  per  cent.  Prepared  as  described  above,  "  pulp " 
ground  lead  may  contain  a  considerable  amount  of  acetate 
of  lead. 

83.  Characteristics  of  Pulp  Lead.  The  easy  working  of 
this  lead  under  the  brush  and  its  apparently  great  white- 
ness has  led  to  its  being  received  with  much  favor,  espe- 
cially in  the  East.  However,  Hooker,  in  discussing  the  value 
of  pulp  ground  lead,  expresses  the  writer's  own  views  on 
the  subject  when  he  states:  "A  critical  comparison  between 
pulp  ground  lead  and  regularly  ground  lead  would  not  seem 
to  justify  this  use  of  pulp  lead  when  durability  and  per- 
manence of  color  are.  concerned."  "  Pulp  lead  "  is  usually 
distinguished  from  regular  lead  by  rather  a  flat,  dull  look 
and  a  little  whiter  color  than  the  other  lead;  it  will  also 
stand  a  little  more  oil  in  first  thinning,  but  "  breaks  " 
suddenly  when  thinned  too  far.  A  small  amount  rubbed 
upon  a  palette  or  glass  with  the  addition  of  just  a  trifle 
of  dry  eosine  (an  aniline  dye  insoluble  in  oil)  shows  at 
once  a  bright  pink  color,  due  to  the  production  of  an 
eosine  lake  by  the  acetate  of  lead  solution  present.  True, 
this  acetate  of  lead  does  not  represent  to  exceed  one  per 
cent  ordinarily  of  the  lead,  but  it  has  a  strong  bearing 
upon  the  saponification  of  the  oil  and  consequent  durability 
of  the  paint.  A  comparison  with  regularly  ground  lead 
shows  no  such  reaction.  Now  place  the  two  leads,  "  regu- 
lar and  pulp  "  ground,  upon  a  glass,  and  note  the  effect, 
when  they  are  rather  rapidly  dried,  as  would  be  the  case 
when  the  glass  is  left  for  a  time  on  the  top  of  a  heated 
radiator.  The  pulp  lead  turns  rapidly  yellow,  showing 
the  yellowing  effect  of  the  heat  on  the  saponified  oil  in 
the  pulp  lead.  The  action  of  gases  such  as  sulphuretted 
hydrogen  present  in  the  atmosphere,  particularly  of  cities, 


MODERN  APPLICATION  OF  THE  DUTCH  PROCESS.        73 

is  very  generally  known,  so  far  as  the  blackening  of  white 
lead  is  concerned,  but  the  marked  difference  between 
different  white  leads  as  regards  susceptibility  to  this 
influence  is  not  generally  known.  Placing  a  little  pulp 
lead  in  oil  upon  glass  beside  regularly  ground  lead  in  oil, 
and  subjecting  both  to  the  influence  of  this  gas  diffused 
in  air,  it  will  be  seen  that  the  pulp  lead  is  badly  blackened 
before  the  action  is  scarcely  appreciable  upon  the  other, 
showing  plainly  how  much  more  susceptible  to  discolor- 
ation the  pulp  ground  lead  is  than  the  other. 

84.  The  points  which  have  created  a  certain  demand 
for  pulp  ground  lead  are,  first,  its  color,  which  is  fictitiously 
white,  in  that  it  loses  this  when  the  water  evaporates, 
besides  discoloring  more  readily  than  any  other;  the  extra 
thinners  which  it  will  carry  and  still  retain  a  certain  peculiar 
brushing  quality;  the  seemingly  greater  covering,  which 
proves  false  when  entirely  dry,  and  the  readiness  with 
which  it  can  be  used  to  produce  a  certain  "  flat  "  finish 
for  inside  work.  The  last  might  be  worth  some  consider- 
ation were  it  not  that  it  is  so  greatly  offset  by  the  sensitive- 
ness of  the  lead  to  discoloration,  and  the  rapidity  with 
which  it  acts  upon  linseed  oil,  due,  doubtless,  to  the  acetate 
that  was  not  removed,  thus  causing  the  paint  to  chalk 
and  perish  far  more  rapidly  than  would  a  regularly  ground 
lead.  Such  lead  should  never  be  used  and  be  expected 
to  stand  any  length  of  time. 


CHAPTER  VII. 

THE  CARTER  PROCESS. 

85.  History.     Numerous  efforts  have   been   made   and 
much  money  spent  in  attempting  to   shorten    the    time 
required  for  the  manufacture  of  white  lead  by  the  old 
Dutch  process,  but  the  various  quick  processes  as  they 
were  termed  did  not  possess  all  of  the  elements  of  success 
and  after  a  short  trial  were  given  up  as  impracticable  or 
unprofitable  on  a  large  scale.     The  Carter  process,  how- 
ever, was  the  first  in  this  country  to  prove  the  exception 
to  the  rule,  and  at  the  date  of  writing,  the  two  plants  of 
the  Carter  Company  in  the  United  States  have  an  aggregate 
yearly  tonnage  of  approximately  twenty  thousand  tons. 

86.  Adams  White  Lead  Company.   The  original  patents 
of  what  is  commonly  known  as  the  "  Carter  Process  >r 
were  taken  out  by  McCreary  &  Adams  in  the  early  seventies 
who  formed  a  corporation  and  operated  a  small  plant  in 
Baltimore,  Md.,  under  the  name  of  the  Adams  White  Lead 
Company.     The  plant  was  operated  for  only  a  short  time. 
A  little  later  another  attempt  was  made  at  Washington, 
Pa.,  which  was   likewise   unsuccessful,  owing   to    imper- 
fections in  the  process  and  crudeness  in  operation,  and 
also  to  lack  of  sufficient  capital. 

87.  Omaha  White  Lead  Company.   In  1878,  S.  E.  Locke 
secured  a  license  from  the  Adams  White  Lead  Company 
to  operate  a  plant  in  Omaha,  Nebr.,  and  to  this  end  organ- 
ized the  Omaha  White  Lead  Company  which  was  com- 
posed of  a  number  of  Omaha  capitalists.     Besides  the 
manufacture  of  white  lead  the  company  dealt  in  glass  and 
painters'  supplies. 

74 


THE  CARTER  PROCESS. 


75 


76  THE  LEAD   AND   ZINC  PIGMENTS. 

A  banker  by  the  name  of  H.  W.  Yates,  being  one  of  the 
largest  owners,  placed  his  nephew,  S.  B.  Hayden,  in  charge 
of  the  company.  Owing,  however,  to  the  lack  of  experi- 
ence the  company  became  financially  embarrassed. 

88.  Formation  of  the  Carter  Company.    Levi  Carter,  at 
this  time  a  member  of  the  firm  of  Coe  &  Carter  of  Omaha, 
large   railroad    contractors,    saw   the   possibilities   of   the 
process  and  secured  in  1885  a  controlling  interest  in  the 
plant  which  then  had  a  capacity  of  about  four  hundred 
tons    yearly.     The    reorganized    company,    the    name    of 
which  had  been  changed  to  the  Carter  White  Lead  Com- 
pany, encountered  exceedingly  bitter  competition  from  the 
then  recently  consolidated  white  lead  interests  but,  due  to 
the  indomitable  character  and  perseverance  of  Mr.  Carter, 
the  company  managed  to  keep  the  plant  in  operation  with 
a  continued  improvement  of  the  products  produced  until 
it  was  destroyed  by  fire  in  1890.     Profiting  by  the  experi- 
ence obtained,  new  capital  was  secured  and  a  plant  of  about 
seven   thousand    tons   yearly   capacity   was   immediately 
built  in  East  Omaha  by  Mr.  Carter,  which  began  operation 
in  the  fall  of  1892. 

89.  The  success  with  the  new  plant  was  immediate,  the 
enterprise  proving  so  profitable  that  the  building  of  a  large 
plant  in  Chicago  was  decided  upon,  and  which  was  com- 
pleted and  put  in  operation  in  1896,  having  a  capacity  of 
about  fourteen  thousand  tons.     Later  a  plant  of  about  five 
thousand  tons  capacity  was  built  in  Montreal  with  the  aid 
of  Canadian  capital. 

90.  Underlying    Principles.     The  principles  underlying 
this  process  are  the  same  as  in  the  old  Dutch  process,  but  by 
increasing  the  area  of  attack  and  the  use  of  a  more  concen- 
trated supply  of  carbon  dioxide,  and  the  continued  removal 
of  the  crust  of  white  lead  from  the  metal,  the  corrosion  into 
white  lead  is  accomplished  in  approximately  twelve  days, 


THE  CARTER  PROCESS. 


77 


78  THE    LEAD    AND    ZINC    PIGMENTS. 

whereas  as  the  old  Dutch  process  requires  one  hundred  to 
one  hundred  and  twenty,  and  the  percentage  of  converted 
lead  is  eighty-five  to  ninety  per  cent  as  against  about 
seventy-five  per  cent  in  the  older  process. 

91.  Granulating  the  Lead.   The  lead,  which  is  of  the  same 
nature  and  grade  as  used  in  the  Dutch  process,  is  melted  in 
a  large  kettle  holding  about  ten  thousand  pounds,  the  pigs 
of  lead  being  conveyed  and  dumped  into  the  kettle  by 
means  of  an  endless  chain.     The  stream  of  molten  lead  as  it 
flows  from  the  kettle  encounters  a  jet  of  high  pressure  steam 
which  disintegrates  it  into  a  coarse  granular  powder,  which 
collects  in  the  hopper-shaped  bottom  of  the  large  blow 
room  and  is  discharged  into  truck  cars  placed  underneath. 
By  the  use  of  a  slight  vacuum  any  fine  particles  of  lead  dust 
are  conveyed  to  a  dust  collector,  thus  avoiding  danger  to 
health  in  the  loading  of  the  cars.     Charges  of  about  four 
thousand  pounds  of  this  "  blown  lead  "  are  placed  in  large 
wooden  drums  ten  or  twelve  feet  long,  and  about  five  or  six 
feet  in  diameter.     Around  the  tub  at  each  end  is  a  heavy 
iron  hoop  resembling  a  car-rail;  these  rest  on  roller  bearings; 
around  the  center  of  the  tub  is  another  hoop,  containing 
gear-teeth,  which  in  turn  mesh  into  the  gears  from  the  large 
driving  shaft  which  runs  the  entire  length  of  the  corroding 
room,  which  contains  nearly  three  hundred  of  these  tubs  or 
drums.     The  drums  revolve  slowly,  making  about  six  revo- 
lutions per  hour,  which  causes  the  lead  to  continually  shift 
position,  that  which  is  carried  up  the  side  of  the  drum  rolling 
again  to  the  bottom.     This  exposes  each  granule  to  the 
action  of  the  corroding  agencies  and  also  by  abrasion  wears 
off  the  coating  of  white  lead  as  fast  as  it  forms,  continually 
exposing  fresh  metal  to  be  acted  upon. 

92.  Corrosion.    Dilute  acetic  acid  and  water  are  sprayed 
into  the  drums  at  intervals  during  the  first  three  days,  30 
per  cent  acetic  acid  being  used,  which  has  been  reduced 


THE  CARTER  PROCESS. 


79 


80  THE  LEAD  AND  ZINC  PIGMENTS. 

one  part  with  four  parts  of  water.  The  amount  used  dur- 
ing the  corrosion  being  one  and  three-quarters  to  two  pounds 
of  30  per  cent  acetic  acid  per  hundred  pounds  of  metallic 
lead,  considerably  more  than  used  in  the  Dutch  process. 
A  current  of  purified  flue  gas  containing  eight  to  ten 
per  cent  of  carbon  dioxide  is  passed  through  the  cylinders, 
entering  through  the  center  of  one  end  and  coming  out  at 
the  other.  This  gas  is  obtained  by  burning  a  very  high 
grade  of  coke,  low  in  sulphur,  under  the  boilers,  and  is  puri- 
fied by  passing  it  through  a  compartment  filled  with  bog 
iron  ore,  which  removes  all  traces  of  sulphur,  and  also  gives 
an  opportunity  for  any  soot  particles  to  deposit.  The  tem- 
perature of  the  gas  will  vary  between  150°  and  200°  F.,  as 
it  is  delivered  to  the  drums.  In  order  to  secure  an  even 
and  uniform  corrosion  the  partially  corroded  mass  is 
removed  from  the  drums  about  the  sixth  day,  and  run 
through  a  pulverizer  to  reduce  any  lumps  or  balls  that  may 
have  been  formed. 

93.  The  disintegrated  material  is  then  replaced  in  the 
drums  and  the  conversion  finished,  the  entire  corroding 
process  taking  about  twelve  days.     Great  care  must  be 
exercised  in  not  adding  too  large  quantities  of  water  or  acid, 
or  granulating  the  lead  too  fine  in  the  first  place,  as  in  such 
instances  the  mass  becomes  so  pasty  as  not  to  work  prop- 
erly in  the  drums,  or  is  "  drowned  out  "  as  the  workmen 
term  it,  which  results  in  an  almost  entire  cessation  of 
chemical  action,   and   can  only  be   "  started  "   again  by 
mixing  with  a  large  amount  of  fresh  lead  and  recorroding. 
The  chemical  actions  that  take  place  are  entirely  similar  to 
those  of  the  old  Dutch  process  and  in  fact,  the  Carter 
process  differs  not  at  all  in  the  fundamental  principles  from' 
the  older  process. 

94.  Washing   and   Floating.     The   finished   product   on 
removal  from  the  drums  is  run  into  large  tanks,  where  it  is 


THE  CARTER  PROCESS. 


81 


82 


THE   LEAD   AND   ZINC  PIGMENTS. 


agitated  with  water  and  then  washed  through  a  rotary 
screen  to  remove  coarse  particles,  the  finer  material  is  then 
passed  through  a  drag  and  float  system  to  remove  the  last 
trace  of  blue  lead  and  as  much  of  the  crystalline  lead  as 
possible.  The  separated  white  lead  is  washed  thoroughly 
to  free  it  from  acetic  acid,  and  the  more  or  less  insoluble 
acetates  of  lead,  which  are  afterwards  precipitated  from  the 
wash  waters  with  carbonate  of  soda.  The  washed  lead  is 
allowed  to  settle  in  large  tanks,  the  supernatent  water 
drawn  off,  and  the  thick  paste  pumped  onto  copper  drying 
pans  and  dried  in  the  usual  manner. 

95.  Chemical  Composition.  In  chemical  composition 
the  ratio  of  carbonate  to  hydroxide  is  fairly  constant,  the 
following  table  showing  the  composition  every  two  weeks 
for  a  period  of  twelve  months. 


Carbonate. 

Hydroxide. 

May    31    1906 

73  59 

26  41 

June  15,  1906 

75  23 

24  77 

June  30,  1906  
July    15,  1906  
July   31,  1906  

76.26 
71.89 
73  23 

23.74 
28.11 

26  77 

Aug.   15,  1906   

69.65 

30  35 

Aug.  31,  1906  

72.86 

27.14 

Sept    15    1906 

71   16 

28  84 

Sept   30    1906 

73  84 

26  16 

Oct     15    1906 

75  11 

24  89 

Oct     31    1906  .  . 

72  50 

27  50 

Nov.  15,  1906  

75  29 

24  71 

Nov.  30,  1906  '.  
Dec.   15,  1906  

74.68 
77.41 

25.32 
22.59 

Dec.   31,  1906  

76.81 

23.19 

Jan     15    1907 

74  44 

25  56 

Jan     31    1907 

74  93 

25  07 

Feb    15   1907  ... 

75  77 

24  23 

Feb.  28    1907  

77  11 

22.89 

Mar.   15,  1907  

75.65 

24.35 

Mar.  31,  1907  

74.62 

25.38 

Apr.    15,  1907  

76.32 

23.68 

Apr    30   1907 

77  72 

22  28 

Average              

74  61 

25.39 

THE  CARTER  PROCESS. 


83 


84  THE  LEAD  AND   ZINC  PIGMENTS. 

It  will  be  noted  that  the  percentage  of  carbonate  is 
slightly  higher  than  in  the  average  grades  of  old  Dutch 
white  lead,  which  together  with  its  freedom  from  blue  lead 
explains  its  clearness  of  tone.  In  the  practical  paint  tests, 
made  by  the  writer,  little  or  no  difference  has  been  observed 
in  its  wearing  or  service  value,  as  compared  with  the  best 
brands  of  old  Dutch  lead;  in  application  it  works  slightly 
easier  under  the  brush,  and  remains  in  suspension  better  in 
the  oil. 

96.  Characteristics.     As  produced  by  this  process,  Carter 
lead  is  usually  whiter  than  old  Dutch  white  lead,  the  parti- 
cles are  much  finer  and  of  a  more  nearly  uniform  size,  and, 
therefore,  100  pounds  of  Carter  lead  in  oil  will  cover  a  con- 
siderable larger  area  of  surface  than  100  pounds  of  old 
Dutch  lead  when  reduced  alike  with  oil.     The  body  or  hid- 
ing power,  however,  is  not  at  all  times  quite  equal  to  that  of 
the  older  lead,  although  the  surface  is  distinctly  a  cleaner, 
clearer  white. 

97.  Success.     This  process  having  proven  very  successful 
financially,  a  plant  was  built  along  similar  lines  by  Harrison 
Brothers  &  Company,  Philadelphia,  in  which  the  Carter 
Company  was  interested  in  a  way,  and  assisted  towards  the 
construction   of   the   plant.     Shortly   afterwards   another 
plant  was  built  at  Buffalo,  by  Kellogg  &  McDougall,  of 
about  three  thousand  tons  capacity,  with  the  assistance  of 
the  same  engineer  who  constructed  the  Harrison  plant. 
Both  of  these  plants  have  been  eminently  successful. 


-'•     CHAPTER  VIII. 

THE  MILD  PROCESS   (ROWLEY). 

98.  ,  Derivation  of  Name.  The  "  Mild  Process  "  for  manu- 
facturing white  lead  is  the  only  one  in  practical  operation 
in  this  country  which  does  not  require  the  use  of  strong 
acids,  alkalies,  or  other  chemicals  in  the  process  of  manu- 
facture, every  trace  of  which  must  be  removed  from  the 
finished  product,  necessarily  involving  certain   purifying 
processes  which  in  themselves  are  expensive  and  costly 
and  if  incomplete  will  cause  a  marked  deterioration  in  the 
quality  of  the  lead  produced. 

99.  This  process  derives  its   name  from  the  very  fact 
that  it  is  the  mildest,  simplest,  most  natural  process  possi- 
ble for  the  manufacture  of  white  lead  —  metallic  lead,  air, 
water  and  carbon  dioxide  gas  being  the  only  substances 
required.     This  process  results  in  the  production  of  one 
uniform  product,  a  strictly  pure  basic  carbonate  of  lead  of 
approved    chemical   and   physical  constitution  and  of   a 
whiteness,  density  and  covering  power  not  exceeded  by 
that  of  any  other  make  of  white  lead. 

100.  Early  Attempts.   The  proposition  of  reducing  gran- 
ulated lead  by  attrition  in  the  presence  of  water  and  car- 
bonating  the   product   obtained   is   a  comparatively   old 
idea  and  numerous  attempts  have  been  made  and  several 
patents  have  been  taken  out  embodying  this  idea,  not  only 
in  England  and  on  the  Continent  but  in  this  country  as 
well.     Pulsifer  in  his  History  of  Lead  records  the  attempts 
of  Welch  and  Evans  of  Philadelphia  in  1814  who  patented 
a  quick  process  of  making  white  lead,  by  which  granulated 

85 


THE  LEAD  AND   ZINC  PIGMENTS. 


THE  MILD  PROCESS    (ROWLEY).  87 

lead  was  placed  in  lead-lined  barrels,  which  were  made  to 
revolve.  The  barrels  were  partly  filled  with  water,  and  the 
particles  of  lead  removed  by  attrition  were  oxidized  by 
oxygen  from  the  air,  and  this  oxide  carbonated  by  the 
introduction  of  carbon  dioxide  produced  from  burning 
charcoal.  Also  that  of  Smith  Gardner,  of  New  York,  who 
took  out  a  patent  in  1840,  for  a  process  by  which  "  granu- 
lated or  small  pieces  of  lead  were  introduced  into  vessels 
lined  with  sheet  lead,  and  partially  filled  with  water,  and 
so  arranged  that  they  could  be  revolved  or  manipulated 
in  such  a  manner  as  to  subject  the  lead  to  continual  attri- 
tion. The  vessels  were  kept  closed,  and  during  the  process 
carbon  dioxide  and  air  were  introduced." 

10 1.  Solution  by  W.  H.  Rowley.     Owing  to  a  lack  of 
knowledge  of  the  correct  principles  by  which  this  process 
must  be  conducted  in  order  to  be  successful  all  of  these 
earlier  attempts  failed  when  put  to  practical  test  on  a 
commercial  scale  and  it  remained  for  Mr.  Willson  H.  Rowley 
of  St.  Louis,  Mo.,  to  overcome  the  difficulties  encountered 
by  his  predecessors  and   put  this   type  of  process  into 
successful  operation  on  a  large  scale. 

102.  Early  Training.    Unlike  the  majority  of  inventors 
who  have  worked  along  the  line  of  attempting  to  render 
the  process  of  white  lead  manufacture  more  rapid   and 
economical,  Mr.  Rowley  had  the  advantage  of  many  years 
experience  in  the  white  lead  industry,  having  been  connected 
with  the  Carter  White  Lead  Company,  besides  having  had 
a  close  acquaintance  with  the  old  Dutch  Process  of  manu- 
facture  through   employment   with   the   Southern   White 
Lead  Company  with  which  his  father,  Mr.  G.  A.  Rowley, 
was  connected  for  some  years. 

103.  Atomization  with  Superheated  Steam.   Mr.  Rowley's 
predecessors   had   been   able   to   obtain   only   a   coarsely 
granulated  lead  to  start  with,  which  could  be  reduced  to 


88 


THE  LEAD  AND   ZINC  PIGMENTS. 


THE  MILD  PROCESS   (ROWLEY).  89 

oxides  or  basic  hydroxides  only  with  great  difficulty  by 
attrition  in  the  presence  of  water  and  air.  His  experi- 
ments, however,  led  him  to  conceive  the  idea  of  atomizing 
or  disintegrating  the  lead  with  the  aid  of  a  current  of  high 
pressure  superheated  steam.  His  experiments  along  this 
line  which  were  carried  out  on  an  extensive  scale  were 
completely  successful  and  the  several  patents  covering 
the  processes  of  manufacture  were  granted  Mr.  Rowley  in 
1902  and  1903. 

104.  Growth   of    Process.     Immediately    thereafter    a 
plant  of    approximately  1000  tons  annual  capacity  was 
equipped  and  placed  in  operation  early  in  the  same  year. 
The  product  found  immediate  consumption  and  by  1907, 
the  sales  having  outgrown  the  producing  capacity  of  the 
plant,  it  was  found  necessary  to  enlarge  the  factory  or 
build   a  new  one.     The   latter  proposition   was   the   one 
decided  upon  as  the  most  feasible  and  resulted   in  the 
building  of  the  present  plant  in  Detroit,  additional  capital 
having  been  interested  in  the  enterprise,  and   the  name 
changed  from  the  Rowley  White  Lead  Company  to  the 
Mild  Process  White  Lead  Company,  affiliated   with  the 
Acme  White  Lead  &  Color   Works.     The   present    plant 
is  one  of  the  largest  and   most   modern  equipped  white 
lead  factories  in  the  world,  having  when  fully  equipped  an 
annual  capacity  of  over  5000  tons.     The  mechanical  de- 
vices installed  for  reducing  the  amount  of  labor  to  a  min- 
imum in  the  handling  and  conveying  of  the  lead  in  the 
different  stages  of  manufacture  render  this  process  the  most 
economical  of  any  in  use  and  at  the  same  time  the  most 
sanitary. 

105.  Simplicity  of  Process.   The  process  by  which  this 
simple  and  progressive  conversion  from  metallic  lead  into 
white  lead  is  accomplished  is  extremely  simple.     The  cor- 
roder  is  not  obliged  to  use  the  extremely  highly  refined 


90 


THE  LEAD  AND   ZINC  PIGMENTS. 


THE  MILD  PROCESS    (ROWLEY).  91 

lead  used  by  the  Dutch  process,  but  may  use  an  ordinary 
good  grade  of  lead;  some  of  the  hard  grades  of  lead,  how- 
ever, do  not  suffer  conversion  as  easily  as  the  softer  vari- 
eties, although  there  is  apparently  little  or  no  difference  in 
the  color  and  quality  of  the  product  obtained. 

106.  Atomizing  the  Lead.   The  lead  is  melted  in  large 
kettles  holding  5,000  pounds  each  from  the  bottom  of  which 
it  is  conveyed  through  heated  pipes  to  the  "  atomizers, " 
which  are  similar  in  principle  to  the  ordinary  laboratory 
blast  lamp.     In  the  atomizers  the  molten  lead  comes  in 
contact  with  a  current  of  steam  superheated  to  a  temper- 
ature higher  than  the  melting  point  of  the  lead.     The 
expansive   force  of   the  steam  disintegrates  the  lead  into 
exceedingly  minute  particles,  which  immediately  solidify. 
Each  of  the  four  atomizers  in  the  present  plant  has  a 
capacity  of  1,500  pounds  of  atomized  lead  per  hour.     The 
streams    of    atomized  lead  are  directed  downward  in  a 
large  steel  room  some  two  stories  in  height,  in  the  bottom 
of  .which  are  about  two  feet  of  water.    By  means  of  a  drag- 
and -screw  conveyor  the  lead,  in  the  form  of  a  very  heavy 
mud,  is  delivered  from  the  blow-basin  to  the  pump-feeder, 
which  keeps  the  particles  suspended  in  the  water  so  that 
the  material  can  be  handled  by  a  rotary  pump,  which 
forces  the  lead  and  water  through  a  pipe  line  to  the  float 
boxes,  where  the  lead  is  deposited  in  the  desired  compart- 
ments, the  water  flowing  back  to  the  blow-basin  again, 
which  insures  against  any  loss  of  lead.     There  are  five 
float  boxes  in  each  of  the  two  lines,  and  when  filled  each 
line  has  a  capacity  of  250,000  pounds  of  lead. 

107.  Oxidizing  and  Hydrating.   By  means  of  gate  valves 
the  lead  is  discharged  into  the  oxidizers  directly  under- 
neath,  six   to   ten   thousand   pounds   to   the  oxidizer   as 
desired.    The  requisite  amount  of  water  is  added,  a  current 
of  air  under  low  pressure  from  a  fan  introduced  and  the 


92 


THE  LEAD   AND   ZINC  PIGMENTS. 


THE  MILD  PROCESS   (ROWLEY).  93 

contents  agitated  mechanically  for  twenty-four  to  thirty- 
six  hours.  The  particles  of  lead  during  the  atomizing 
process  have  already  become  coated  with  a  thin  pellicle 
of  suboxide  which  renders  the  lead  very  active  chemically, 
so  that  within  a  very  few  hours  after  the  beginning  of  the 
agitation  a  strong  chemical  action  sets  in  accompanied  by 
a  marked  rise  in  temperature,  resulting  in  the  formation 
of  any  of  several  basic  hydroxides  of  lead  as  may  be  desired, 
which  will  vary  in  color  from  greenish  yellow  through  the 
different  shades  of  yellow  orange,  to  a  brownish  orange, 
these  results  being  secured  by  varying  the  amount  of 
water,  air,  agitation  and  control  of  the  temperature.  Some 
of  these  basic  hydroxides  are  much  more  suitable  for  white 
lead  making  than  others.  At  the  expiration  of  the  twenty- 
four  to  thirty-six  hours,  according  to  the  size  of  the  charge, 
about  eighty  to  ninety  per  cent  of  the  lead  will  have  been 
converted  and  the  oxidizers  are  discharged  into  a  trough 
emptying  into  the  float  system,  where  by  means  of  an 
inclined  drag,  two  agitator  tubs  and  a  float-table  the  metal- 
lic lead  is  separated  from  the  basic  oxide  and  returned 
to  the  float  boxes,  to  be  added  to  a  fresh  charge  of  atomized 
lead  in  the  oxidizers. 

1 08.  The  separated   basic   hydroxide   is   conveyed   by 
means  of  another  rotary  pump  to  the  fourth  floor  where 
it  is  deposited  in  a  series  of  large  tanks,  the  water  being 
returned  to  the  separating  system  again  thus  avoiding  any 
mechanical  loss  of  lead. 

109.  Carbonating.   The  above-mentioned  tanks  also  act 
as  a  storage  for  the  basic  hydroxide,  which  is  drawn  as 
required  into  the  carbonators  located  on  the  floor  below. 
The  carbonators  are  large  cylinders  somewhat  similar  to 
the  oxidizers  in  construction  but  of  less  capacity;  in  them 
the  basic  hydroxide  of  lead  is  agitated  in  the  presence  of 
flue  gas  containing  about  eighteen  per  cent  of  carbon 


94 


THE   LEAD   AND   ZINC  PIGMENTS. 


THE  MILD  PROCESS    (ROWLEY).  95 

dioxide.  By  means  of  scrubbers  the  flue  gases  are  thor- 
oughly cooled,  desulphurized  and  freed  from  soot  particles. 
For  the  first  twenty-four  hours  no  apparent  change  is 
noticed  in  the  color  but  in  the  next  twelve  hours  the 
change  is  very  rapid  and  is  accompanied  by  a  remarkable 
swelling  or  increase  in  volume  of  the  mass,  the  carbonators 
requiring  to  be  watered  at  short  intervals,  both  on  account 
of  the  swelling  of  the  mass  and  the  combining  of  the  water 
with  the  lead.  In  approximately  thirty-six  hours  the 
carbonation  is  complete4,  resulting,  if  the  operation  has  been 
properly  conducted,  in  an  exceedingly  white  basic  carbon- 
ate of  lead  of  very  closely  the  theoretical  composition. 
As  there  are  no  impurities  present,  no  washing  or  floating 
is  necessary,  and  on  withdrawal  from  the  carbonators  the 
white  lead  is  pumped  directly  onto  the  dry  pans  arid  dried 
in  the  usual  manner;  when  dry  it  crumbles  instantly  under 
the  slightest  pressure  into  a  very  fine  powder  and  there- 
fore does  not  have  to  be  run  through  a  disintegrating 
mill  before  it  is  barreled  dry. 

no.  Control.  The  "  Mild  Process  "  is  under  a  much 
more  complete  control  than  any  of  the  other  processes, 
as  any  slight  variations  that  may  take  place  in  the  chem- 
ical actions  involved  can  be  easily  corrected  and  counter- 
balanced. At  first  thought  it  might  seem  that  a  white 
lead  produced  in  this  manner  would  consist  largely  of  a 
mixture  of  hydroxide  and  normal  carbonate,  but  such  is 
not  the  case  as  may  be  demonstrated  both  by  a  micro- 
scopical examination  and  by  a  close  study  of  the  process 
of  formation  of  the  white  lead.  The  composition  of  the 
basic  hydroxide  formed  indicates  a  hydration  of  ten  to 
twelve  per  cent,  or  about  one-third  of  the  amount  to  be 
found  in  the  finished  white  lead.  Therefore  the  larger 
part  of  the  hydroxide  portion  of  the  molecule  is  formed 
during  the  carbonating  process  and  this  has  much  to  do 


96 


THE  LEAD  AND   ZINC  PIGMENTS. 


THE  MILD  PROCESS    (ROWLEY). 


97 


98  THE   LEAD   AND    ZINC   PIGMENTS. 

with  the  large  apparent  increase  in  volume,  as  it  is  possible 
by  a  long  continued  carbonation  to  form  a  very  crystal- 
line carbonate  containing  very  little  hydroxide,  the  oper- 
ation being  accompanied  by  a  considerable  diminution  of 
apparent  volume. 

in.  Advantages  of  Process.  From  a  manufacturing 
standpoint  this  process  has  much  to  commend  it,  espe- 
cially as  regards  the  following  items : 

1.  The  process  is  not  restricted  to  a  specially  refined 
lead. 

2.  It  is  under  complete  control. 

3.  It  results  in  conversion  into  white  lead  of  all  of  the 
metallic  lead  during  the  process,   avoiding  any  metallic 
residues  whatever. 

4.  The  white  lead  produced  is  of  a  uniform  grade  —  no 
tailings  or  sandy  lead. 

5.  No  mechanical  losses  of  lead  as  the  same  water  is 
used  over  and  over  again,  there  being  no  impurities  of 
consequence  present. 

6.  Manual  labor  is  reduced  to  a  minimum,  the  conveying 
of  the  material  in  the  process  being  accomplished  entirely 
by  gravity  and  pumps. 

7.  The  process  can  be  made  entirely  sanitary  as  the  work- 
men need  not  come  in  contact  with  the  lead  in  any  part  of 
the  process,  nor  is  there  any  dust  produced  that  contains 
lead  particles,  except  in  the  final  barreling  operations. 

8.  Nothing  is  required  in  the  manufacture,  aside  from 
the  machinery,  power  and  labor,  that  involves  any  expense 
except  the  cost  of  lead  itself. 

112.  Not  a  Precipitation  Process.  The  Mild  process 
should  not  be  confounded  with  any  of  the  so-called  precipi- 
tation processes,  as  it  bears  no  analogy  to  them,  the  lead 
not  being  in  solution  at  any  stage  of  the  process.  As  com- 
pared with  other  white  leads,  Mild  process  white  lead  is 


THE  MILD  PROCESS   (ROWLEY). 


99 


100  THE  LEAD   AND   ZINC  PIGMENTS. 

whiter  than  old  Dutch  white  lead,  being  equal  to  Carter 
lead  in  this  respect.  The  particles  are  of  very  uniform  fine- 
ness, being  slightly  smaller  than  Carter,  and  much  finer 
than  old  Dutch  lead.  Although  very  soft  and  chalky  in 
appearance  and  "  feel,"  it  is  as  dense  and  does  not  require 
any  greater  quantity  of  oil  in  the  grinding  and  little,  if  any, 
more  in  reducing  to  painting  consistency,  than  old  Dutch  or 
Carter  leads,  and  is  sold  in  the  same  sized  kegs.  Under  the 
brush  it  works  easier,  and  owing  to  the  uniform  fineness  of 
the  particles,  it  covers  more  surface  with  an  equal  hiding 
power  than  any  old  Dutch  process  lead  that  the  writer  is 
familiar  with. 


CHAPTER   IX. 

MATHESON   PROCESS. 

113.  Matheson  white  lead  is  the  product  of  one  of  the 
newer  methods   of    corroding,   which   are   popularly   but 
inaptly  called  "  quick  processes  "  in  order  to  distinguish 
them  from  the  older  or  Dutch  process. 

114.  Nature  of  Process.     In  all  of  the  so-called  quick 
processes,  the  metal  is  reduced  to  smaller  particles,  and, 
therefore,  exposes  a  greater  surface  to  the  action  of  the 
corrosive  elements  than  is  the   case  with  the  "  buckle  " 
used  in  the  Dutch  method,  so  that  the  corrosion  of  a  given 
weight  of  metal  is  more  quickly  accomplished.     However, 
the  corrosion  of  so  much  lead  as  is  exposed  directly  to  the 
action  of  the  corroding  agents  must  progress  substantially 
as  rapidly  in  either  method,  and  if  the  newer  processes  used 
the    "  buckle  "    instead  of   smaller  units,  their  corrosion 
would  be  no  quicker  than  by  the  Dutch  method.     Some  of 
them,  and  notably  the  Matheson,  would,  however,  still 
differ  from  the  Dutch  process  in  being  practically  continu- 
ous and  permitting  the  recovery  of  the  carbonate  as  rapidly 
as  made,  and  to  that  extent  they  could  justly  be  designated 
"  quick  "  in  contrast  with  the  older  method,  in  which  more 
than  one  hundred  days  must  elapse  before  the  basic  car- 
bonate of  lead,  or  white  lead  (which  has  been  accumulating 
on  the  buckles  as  the  water  and  acetic  acid  vapors  and  car- 
bonic acid  gas  force  their  way  through  the  outer  layers  of 
carbonate  and  continue  to  attack  the  inner  core  of  metallic 
lead  until  they  can  no  longer  reach  it)  can  be  made  avail- 
able for  marketing. 

101 


102  THE  LEAD   AND   ZINC  PIGMENTS. 


FIG.  38.  —  MELTIXG  ROOM.  —  MATHESON  PROCESS. 


FIG,  39.  —  CORRODING  TANKS,  —  MATHESON  PROCESS. 


MATHESON  PROCESS.  103 

115.  Development  in  United  States.     Another  point  of 
difference  between  the  Matheson  process  and  some  of  the 
older  methods  is  that  it  is  more  controllable,  and  can  thus 
be  made  to  yield  a  product  more  uniform  than  is  obtained 
by  those  methods  which  are  not  open  to  inspection  or  regu- 
lation   while    they    are    working.      The    process    itself   is 
modeled  upon  some  of  the  processes  in  use  in  France,  but 
was  modified  by  Mr.  Ellert  W.  Dahl,  a  Norwegian  chemist, 
who  introduced  it  into  this  country  in  about  1893,  and  who 
for  a  number  of  years  marketed  his  product  here  under  the 
name  "  Premier  White  Lead."     In  1898,  it  was  purchased 
by  the  William  J.  Matheson  Company,  and  has  since  been 
known  under  their  name.     The  process  has  been  subjected 
to  some  changes  in  its  mechanical  detail  which  have  been 
developed  on  the  larger  scale  upon  which  it  has  been  manu- 
factured, but  the  product   upon  analysis  does  not  differ 
from  its  original  composition,  which  conforms  fairly  closely 
to  the  accepted  chemical  formula  for  white  lead,  and  its 
chemical  behavior  is  comparative  with  that  of  any  other 
hyd rated  carbonate  of  lead  that  is  properly  made. 

1 1 6.  Characteristics    of    Matheson    Lead.     Its    physical 
characteristics  are  widely  different,  however,  as  it  is  whiter 
and  finer,  and  is  free  from  the  gritty  particles  of  the  Dutch 
process,  which  are  the  result  of  the  long  exposure  to  con- 
tinued action  of  the  acid  and  gas,  of  the  outer  layers  of  car- 
bonate formed  on  the   "  buckles."     In  specific    gravity, 
Matheson  lead  is  somewhat  lighter  than  Dutch  process,  its 
bulk  being  correspondingly  greater  and  its  oil  carrying 
power  exceeding  that  of  the  heavier  leads  by  about  33 J  per 
cent.     In  other  words,  88  pounds  of  Matheson  dry  lead  will 
require  about  60  pounds  of  oil  to  put  into  the  form  of  paint, 
properly  reduced,  and  92  pounds  of  Dutch  process  lead  will 
require,  45  pounds  of  oil  to  make  a  paint  of  equal  consis- 
tency.    The  resultant  product  measures  over  9J  gallons 


104  THE  LEAD   AND   ZINC  PIGMENTS. 


FIG.  40.  —  WASHING  PRESSES.  —  MATHESON  PROCESS. 


FTG.  41. —  SETTLING  TANKS.  —  MATHESON  PROCESS. 


MATHESON  PROCESS.  105 

with  Matheson  lead,  to  less  than  8  gallons  of  the  Dutch,  or 
about  25  per  cent  more  volume  of  paint,  which  is  claimed 
by  the  manufacturers  to  cover  at  least  a  correspondingly 
greater  surface  with  equal  opacity.  It  should  be  remem- 
bered, however,  that  the  above  increase  in  volume  is  due 
to  the  increased  amount  of  oil  used. 

117.  Manufacture.    In  the  Matheson  process,  the  metallic 
lead  is  "  feathered,"  or  brought  into  a  form  resembling  a 
sponge  in  structure,   by  running  the  molten  metal  into 
water.     This  lead  is  brought  into  contact  with  dilute  acetic 
acid  in  large  corroding  tanks  or  tubs.     In  the  presence  of 
air  and  steam  a  basic  acetate  of  lead  is  produced,  this,  in 
turn,  being  transformed  into  hydrated  carbonate  by  con- 
tact with  carbonic  acid  gas  obtained  from  coke  furnaces. 
The  carbonate  is  then   repeatedly   washed,    after   which 
most  of  the  water  is  removed  by  filter  presses,  and  it  is 
then  dried  in  vacuum  driers.     The  whiteness  of  the  lead 
results  from  its  complete  corrosion,  and  the  consequent 
absence  of  "  blue  "  lead  in  the  carbonate,  as  well  as  to 
its  freedom  from  tan-bark  or  other  organic  matter.     The 
grinding  process  does  not  differ  from  that  employed  with 
other   leads,  except    as    to    the    greater    amount    of    oil 
required,  to    which    reference    has    already    been   made. 
Special  precautions  must  be  observed  in  freeing  the  white 
lead  from  residual  acetates,  which  if  not  completely  removed 
will  be  more  than  likely  to  give  serious  trouble  when  used 
in  paints. 

118.  During  the  corrosion  of  the  lead  by  this  process, 
there  is  produced  a  considerable  quantity  of  a  crystalline 
practically  insoluble  basic  acetate,  which  the  author  under- 
stands is  separated   and   calcined  into  litharge,  together 
with  a  certain  amount  of  metallics  which  are  difficult  of 
conversion  affording  a  most  excellent  grade  according  to 
the  samples  examined  by  the  writer. 


106 


THE  LEAD  AND   ZINC  PIGMENTS. 


FIG.  42. —  VACUUM  DRIERS  AND  FILLING  MACHINE.  —  MATHESON  PROCESS. 


FIG.  43.  —  PULP  MILL. — M \THFSON  PROCESS. 


MATHESON  PROCESS.  107 

119.  Uses.  Several  examinations  of  Matheson  -  lead  by 
the  writer  have  shown  it  to  be  quite  uniform  in  compositien, 
approximating  72.50  per  cent  carbonate  to  27.50  per  cent 
hydroxide.  The  product  is  of  exceptional  whiteness,  and 
free  from  impurities  other  than  basic  acetates  of  lead.  It 
not  only  takes  a  much  larger  amount  of  oil  in  grinding  than 
other  leads,  but  a  much  larger  amount  in  reducing  to  paint- 
ing consistency.  For  these  reasons  the  writer  understands 
that  it  finds  its  larger  use  in  mixed  paints  and  semi-paste 
goods,  where  these  features  are  desirable,  rather  than  as 
strictly  pure  lead  in  oil.  Its  hiding  power  or  opacity  is 
excellent  when  its  spreading  qualities  due  to  the  large 
amount  of  oil  required  are  considered. 


CHAPTER  X. 

THE   SUBLIMED  LEAD  PIGMENTS. 

120.  Sublimed  White  Lead.   The  invention  of  sublimed 
white  lead  is  due  to  Mr.  E.  0.  Bartlett,  who,  while  manager 
of  the  Keystone  Zinc  Company's  works  at  Birmingham, 
Pa.,  in  1866,  became  impressed  with    the    idea    that    a 
lead  pigment  could  be  made  by  the  same  process  as  that 
used  for  making  zinc  oxide,  i.e.,  by  sublimation  of  the  ore 
in  an  oxidizing  fire  and  collection  of  the  condensed  product 
in  cloth  filters  or  bags. 

121.  Early    Development.   In    the    latter    part    of    the 
sixties  he  associated  himself  with  the  firm  of  John  T. 
Lewis  &  Bros.,  of  Philadelphia,  for  the  purpose  of  carry- 
ing out  experiments  along  that  line.     A  small  plant  was 
built  which  was  afterwards  removed  to  Joplin,  Mo.,  and 
enlarged  under  the  financial  backing  of  Mr.  Lewis,  and  the 
experiments  continued  on  a  commercial  scale.     The  loca- 
tion of  Joplin  was  chosen  because  that  city  was  in  the 
heart    of    the    enormously    productive    mining   region    of 
Southwestern    Missouri,  and  also   because  the   lead    ores 
produced  in  that  section  were  exceedingly  free  from  other 
metals  yielding  volatile  oxidation  products  which  would 
contaminate    the   sublimate.     The   single    exception    was 
zinc  which  is,  consequently,  found  as  oxide  in  all  sub- 
limed white  lead  at  present  on  the  market  to  the  extent  of 
approximately  five  per  cent. 

122.  The  first  patent  for  the  process  was  taken  out  in 
1870  and  since  that  time  there  has  been  an  almost  contin- 
uous series  of  patents  for  improvements  in  the  process 

108 


THE  SUBLIMED   LEAD  PIGMENTS. 


109 


110  THE   LEAD   AND   ZINC  PIGMENTS. 

taken  out  at  short  intervals.  The  pigment  has  been  on 
the  market  commercially  in  this  country  for  twenty-five 
years,  although  the  quantity  produced  was  relatively 
small  until  1900.  Since  that  date  the  production  of  sub- 
limed white  lead  has  rapidly  increased. 

123.  Sublimation  of  the  Ore.   The  ore  used  in  the  manu- 
facture of  sublimed  white  lead  is  a  high  grade  of  galena 
(native  lead  sulphide)  which  has  been  crushed  and  "  jigged" 
so  as  to  free  it  from  accompanying  rocks.     This  separation 
is  complete  as  regards  interfering  compounds,  except,  as 
mentioned  above,  in  the  case  of  zinc.     The  finely  pulver- 
ized ore  is  fed  into  the  furnace  along  with  the  necessary 
amounts  of  fuel  and  fluxes.     The  furnaces  are  of  a  special 
type  which  is  a  compromise  between  the  furnace  employed 
for  zinc  oxide  and  the  blast  furnace  used  in  smelting 
roasted  lead  ores.     The  fire  box  has  a  circular  water  jacket 
supplied   with   tuyeres   which   inject   a   powerful   hot-air 
blast  from  all  sides.     The  intense  heat  generated  instantly 
volatilizes  the  lead  sulphide  in  gaseous  form,  which,  as  it 
rises  from  the  incandescent  hearth,  comes  in  contact  with 
the  oxygen  of  the  air  from  the  blast,  and  at  the  enormously 
high  temperature,  is  oxidized  to  what  the  manufacturers 
claim  is  an  oxysulphate,  which,  after  rising  several  feet  in 
the  cylindrical  furnace  lined  with  fire  brick,  passes  into  a 
large  transverse  brick  lined  flue. 

124.  Condensation  of  Fume.   The  heat  of  the  combus- 
tion and  oxidation  is  so  great  that  the  furnace  and  trans- 
verse flue  or  chamber  are  completely  filled  with  flame  and 
hence  it  is  difficult  to  decide  at  just  what  point  the  com- 
bination is  complete.    After  traversing  this  long  horizontal 
chamber,  the   vapor  or  "  white   fume  "  as  it  is  usually 
called,   passes    through   a   series   of  large  air-cooled  iron 
pipes  or  flues  and  through  what  are  termed  the  "  goose- 
necks," which  are  so  arranged  that  the  coarser  particles 


THE  SUBLIMED   LEAD  PIGMENTS. 


Ill 


112  THE  LEAD  AND   ZINC  PIGMENTS. 


FIG,  46.  —  GOOSENECKS.  —  PICHEB  LEAD  COMPANY. 


THE  SUBLIMED  LEAD  PIGMENTS.  113 

containing  impurities  settle  out  and  the  "  white  fume  " 
itself  floats  along,  aided  by  powerful  suction  fans,  for  a 
total  distance  of  between  700  and  1000  feet  when  the 
gases  and  "  fume  "  are  sufficiently  cooled  to  permit  of  the 
collection  of  pigment  particles  in  fabric  condensers,  allow- 
ing the  gases  to  escape  through  their  meshes. 

125.  Bag  Room.     The  condensers  or  collectors   are  in 
the  form  of  long  bags,  hung  perpendicular  in  a  large  build- 
ing known  as  the  bag  house.     The  bags  are  shaken  at 
regular  intervals  to  detach  the  pigment  from  the  sides, 
the  pigment  collecting  below  the  bags  in  large  hoppers 
from  which  it  is  drawn  into  steel  lined  carts  on  the  floor 
below  and  packed  in  barrels  which  hold  about  five  hundred 
pounds.     The  atmosphere  of  the  bag  rooms  is  unbearable 
except  for  short  intervals  by  reason  of  the  sulphur  dioxide 
in  the  escaping  gases. 

126.  Uniformity  of  Product.   Naturally,  the  ratio  of  the 
lead  sulphate  to  lead  oxide  in  sublimed  white  lead  is 
dependent  largely  upon  three  factors,  the  nature  of  the  ore 
fed  into  furnaces,  i.e.,  whether  it  is  entirely  lead  sulphide 
ore  or  whether  other  lead   compounds   are   added;   the 
amount  of  air  which  comes  in  contact  with  the  ore ;  and 
the  temperature   at   which   the   reactions   take   place  in 
the  furnace.    These  conditions  being  under  control  of  the 
manufacturer,  the  product  can  be  kept  quite  uniform  and 
of  the  desired  composition  under  favorable  furnace  con- 
ditions, although  it  is  probable  that  atmospheric  changes 
exert  more  or  less  influence  on  the  nature  of  the  finished 
product. 

The  range  of  variation  in  samples   examined   by  the 
writer  is  as  follows : 

Lead  sulphate 75  to  80  per  cent 

Lead  oxide 20  to  14  per  cent 

Zinc  oxide 5  to    6  per  cent 


114  THE  LEAD   AND   ZINC  PIGMENTS. 


FIG.  47.  —  BAGROOM.  —  PICKER  LEAD  COMPANY. 


THE  SUBLIMED  LEAD  PIGMENTS.  115 

127.  Chemical  Constitution.   As  heretofore  stated,  sub- 
limed white  lead  is  claimed  to  be  a  basic  sulphate  of  lead. 
In  substantiation  of  this  claim  it  is  argued  that  all  of  the 
lead  oxides  known  to  chemists  are  red  or  brown  and  a 
white  oxide  of  lead  is  as  yet  unknown;  further,  that  a 
mixture  of  sublimed  white  lead  in  oil  dries  normally  in 
about  the  same  length  of  time  as  required  for  corroded  white 
lead,  —  two  days,  —  while  a  mixture  of  lead  sulphate,  lith- 
arge (lead  monoxide)  and  zinc  oxide,  in  the  same  propor- 
tions as  those  shown  by  an  analysis  of  sublimed  white 
lead,  dries  in  from  ten  to  twelve  hours.     Recent  work  by 
Chevalier  indicates  that  the  fume  from  a  furnace  roasting 
lead  sulphide  has  the  formula  Pb3S209,  apparently  a  com- 
plex of  two  molecules  of  sulphate  with  one  of  oxide.     The 
conditions  of  the  production  of  the  two  fumes  are  not 
essentially  different  and  it  is  claimed   by   the  sublimed 
white  lead  makers  that  they  have  isolated  this  compound 
in  a  state  of  purity  although  not  on  a  commercial  scale. 
If  the  existence  of  this  basic  sulphate  is  a  fact,  then  com- 
mercial sublimed  white  lead  is  a  mixture  of  it  with  a  vary- 
ing amount  of  neutral  lead  sulphate. 

These  arguments,  while  presumptive,  can  hardly  be 
accepted  as  entirely  conclusive.  The  reactions  and  com- 
binations that  take  place  at  exceedingly  high  temperatures 
are  but  imperfectly  understood  and  it  is  entirely  possible 
that  we  may  have  aggregates  formed  at  high  temperatures 
in  which  the  components  are  so  intimately  associated  that 
they  are  apparently  chemically  combined  without  such 
actually  being  the  case. 

128.  Yearly  Production.   Many  improvements  have  been 
made  in  the  process  of  manufacture  during  the  past  few 
years,  which  have  resulted  in  an  increased  demand  for 
sublimed    white  lead  on  the  part  of    the  paint  manufac- 
turers as  shown  by  the  table  on  page  117. 


116 


THE  LEAD  AND   ZINC  PIGMENTS, 


THE  SUBLIMED   LEAD  PIGMENTS. 


117 


Year. 

Production  in  i>oimds. 

Value. 

1902 

9,465,500 

$449,611.00 

1903 

8,592,000 

386,640.00 

1904 

12,954,000 

550,589.00 

1905 

13,954,000                       732,585.00 

1906 

15,974,000                      958,440.00 

1907 

17,400,000                   1,026,600.00 

129.  Physical  Characteristics.   As  prepared  at  the  present 
time,  sublimed  white  lead  is  a  very  finely  divided  substance 
entirely  amorphous  in  structure.     In  color  it  is  not  quite 
as  white  as   a  good  white  lead.     This  may  in  part    be 
accounted  for  by  the  fact  that  it  contains  about  0.06  per 
cent  of  ferric  oxide.     Its  specific  gravity  is  slightly  less 
than  corroded  white  lead,  being  6.2.     The  average  diam- 
eter of  the  particles  is  about  one  thirty-five  thousandth  of 
an  inch  while  those  of  white  lead  vary  in  the  same  sample 
between  one  four  hundredth  and  one  fifteen  thousandth  of 
an  inch.     It  is  for  this  reason,  probably,  that  paints  made 
wholly  or  largely  of  sublimed  white  lead  show  brush  marks 
more  plainly  than  white  lead  paints.     It  requires  more  oil 
in  grinding  than  ordinary  white  lead  but  not  sufficient  to 
give  it  excessive  spreading  qualities. 

130.  After  having  once  been  packed  together  in  barrels, 
it  is  much  less  poisonous  than  corroded  white  lead ;  which 
fact  is  not  of  so  great  moment  as  formerly  because  with 
modern  appliances  for  ventilation  in  the  manufacturing  and 
painting  establishments  and  increasing  cleanliness  on  the 
part  of  the  workmen,  lead  poisoning  has  largely  ceased  to 
be  the  formidable  evil  that  it  once  was  in  this  country. 

131.  Uses    of  Sublimed    White   Lead.     Because   of    the 
exceeding  fineness  of  its  particles,  sublimed  white  lead  is 
seldom  ground  straight  in  linseed  oil  but  it  is  generally 
ground  with  other  pigments,  and  hence  finds  its  largest 


118  THE   LEAD   AND    ZINC   PIGMENTS. 

use  in  the  manufacture  of  mixed  paints;  and  because  this 
fineness  allows  the  pigment  to  remain  in  suspension  in  the 
vehicle,  it  is  a  favorite  constituent  for  dipping  paints. 
Owing  to  its  comparative  inertness  to  sulphurous  vapors 
and  gases  and  having  a  hiding  power  substantially  equal 
to  white  lead,  sublimed  white  lead  is  rapidly  coming  into 
extensive  use  in  railroad  specifications.  It  is  also  finding 
a  wide  use  in  the  structural  iron  and  steel  paints. 

132.  Chalking.  The  objections  frequently  urged  against 
this  pigment  are  that  it  chalks,  that  it  is  not  equal  in 
whiteness  to  white  lead,  and  that  paints  containing  it 
thicken  up  and  work  stiff  and  greasy  in  cool  weather  or 
during  the  cooler  portions  of  the  day.  While  chemist  at 
North  Dakota  Experiment  Station,  the  writer  was  closely 
associated  with  Professor  E.  F.  Ladd  in  the  conducting  of 
a  large  number  of  practical  exposure  tests  in  which  sub- 
limed white  lead  was  applied  straight  and  in  a  number  of 
combinations.  As  a  result  of  these  and  other  practical 
tests  the  writer  believes  that  sublimed  white  lead  does 
chalk  even  more,  possibly,  than  old  Dutch  process  white 
lead,  but  the  chalking  is  of  an  entirely  different  character. 
When  ordinary  white  lead  begins  to  chalk  vigorously,  it 
will  be  found  that  the  paint  film  has  lost  its  elasticity,  and 
has  become  brittle  and  friable  throughout;  also,  that  the 
luster  of  the  film  under  the  chalk-like  coating  has  entirely 
disappeared.  A  sublimed  white  lead  film,  on  the  other 
hand,  retains  much  of  its  original  elasticity  under  the 
chalk  coating,  indicating  that  the  disintegration  is  con- 
fined to  the  surface,  and  it  is  possible  that  the  retention  of 
the  "  chalk  "  on  the  surface  gives  some  protection  to  the 
unaffected  coat  below.  When  used  with  other  pigments, 
the  chalking  of  sublimed  white  lead  is  retarded  and  it 
behaves  almost  exactly  like  old  Dutch  process  white  lead 
under  similar  conditions. 


THE  SUBLIMED   LEAD  PIGMENTS.  119 

133.  Comparative  Whiteness.   Sublimed  white  lead,  when 
applied  straight,  is  not  of  equal  whiteness  as  compared 
with  old  Dutch  white  lead,  having  a  slightly  yellowish, 
creamy  tone.     After  one  year's  exposure,  however,  the 
result  is  reversed.     The  sublimed  white  lead  is  then  the 
whiter  and  has  lost  its  creamy  tint;  while  the  old  Dutch 
process  white  lead  has  taken  on  its  customary  grayish 
tone. 

Paints  containing  a  large  percentage  of  sublimed  white 
lead,  according  to  the  experience  of  the  writer,  show  a 
distinct  tendency  to  thicken  and  work  stiffer  under  the 
brush  during  cool  weather.  This  may  be  due  to  the 
exceeding  fineness  of  the  particles.  If  so,  the  change  is 
physical  rather  than  chemical  and  hence  not  a  serious 
matter  when  handled  understandingly  by  the  master 
painter  and  when  it  is  considered  that  most  painting  is 
done  in  warm  weather. 

134.  Inertness    toward    Tinting    Colors.     Due    to    the 
chemical  stability  of  sublimed  white  lead,  it  has  little 
injurious  effect  on  the  tinting  colors  which  it  may  be  ground 
with:  as  is  well  known,   chrome  yellow,  chrome  green, 
Prussian  or  Chinese  blue  and  some  organic  colors  do  not 
give  permanent  tints  when  ground  with  white  lead,  due  to 
chemical  interaction  between  the  color  pigment  and  the 
white  lead.     Addition  of  chemically  inert  pigments  lessen 
the  action  in  the  case  of  white  lead  but  do  not  entirely 
inhibit  it.     For  this  reason  sublimed  white  lead  has  come 
widely  into  use  in  mixed  paints,  especially  in  the  tints 
replacing  a  portion  of  the  white  lead  and  thus  increasng 
the  permanence  of  the  tint. 


120  THE   LEAD   AND    ZINC  PIGMENTS. 

SUBLIMED    BLUE    LEAD. 

135.  Sublimed  blue  lead  is  a  pigment  finding  considera- 
ble use  as  a  protective  coat  for  metallic  surfaces.     Its 
manufacture  is  by  methods  analogous  to  those  employed 
for  the   manufacture  of  sublimed  white  lead,  but  in  this 
case  the  sublimation  is  conducted  in  a  reducing  instead  of 
an  oxidizing  atmosphere. 

136.  Properties.   Because  of  the  large  amount  of  un- 
saturated    sulphur    compounds    which    it    contains,    the 
sublimed  blue  lead  coat  is  quite  different  from  that  of  any 
other  paint  made  with  linseed  oil.     Apparently  the  sul- 
phides and  sulphites  contained  in  it  affect  the  oil  so  that, 
after  drying,  it  is  comparatively  immune  from  action  by 
coal  gas.     However  useful  the  presence  of  these  ingredients 
may  be  after  the  coat  is  applied,  they  are  a  considerable 
detriment  in  the  eyes  of  the  paint  maker,  as  this  material 
has  a  very  great  tendency  to  cause  the  paint  to  thicken, 
or  liver,  if  allowed  to  stand  after  being  thinned.     For  this 
reason,  sublimed  blue  lead  is  not,  as  a  rule,  sold  straight  in 
liquid  form,  but  is  packed  either  as  paste  or  else  ground 
with  a  percentage  of  graphite  or  red  lead. 

137.  Composition.   In  composition,  sublimed  blue  lead 
varies  somewhat,  but  the  analysis  is  about  as  follows: 

Per  cent. 

Lead  sulphate 50 

Lead  oxide 35 

Lead  sulphide 5 

Lead  sulphite 5 

Carbon 3 

Zinc  oxide .  .  2 


100 

The  production,  in  1907,  was  2,422,000  pounds,  valued  at 
$135,632. 


THE  SUBLIMED  LEAD  PIGMENTS.  121 

SUBLIMED   LEAD    OXIDE. 

138.  Sublimed  lead  oxide  is  a  sublimate  obtained  as  a 
by-product  from  the  manufacture  of  litharge  by  the  hearth 
or  cupellation  process.  It  is  an  exceedingly  fine,  sulphur- 
yellow  material,  and  desirable  for  many  purposes,  particu- 
larly color  making. 

Unfortunately,  it  is  not,  as  yet,  produced  as  a  regular 
article  of  commerce  on  a  large  enough  scale  to  attract  atten- 
tion, although  litharge  manufacturers  are  working  toward 
this  end. 


CHAPTER    XL 

WHITE   LEAD   MANUFACTURE  IN  EUROPE. 

139.  Comparative    Costs    of   Manufacture.     The    manu- 
facture of  white  lead  in  England  and  on  the  Continent  is 
conducted  in  a  much  different  manner  than  in  this  country. 
The  majority  of  European  white  lead  plants  are  much 
smaller  than  the  average  plants  in  the  United  States,  and, 
especially  in  England,  are  conducted  on  a  much  more  con- 
servative scale  with  regard  to  labor-saving  machinery  and 
appliances;  so,  notwithstanding  a  lower  European  wage 
scale,  American  white  lead  plants  undoubtedly  enjoy  a 
lower  cost  of  production.     Government  regulations  safe- 
guard as  carefully-  as  possible  the  health  of  the  employees, 
whereas  in  this  country  there  are  substantially  no  restric- 
tions, although  there  is  at  the  present  time    a   manifest 
tendency  to  legislate  in  this  direction. 

140.  English  Regulations.     The  following  abstracts  from 
the  English  regulations  (1906),  in  addition  to  those  quoted 
in  the  chapter  on  White  Lead  Poisoning,  will  afford  some 
idea  of  the  safeguards  placed  around  the  employees  who 
work  with  lead  products. 

"  No  dry  lead  color  shall  be  placed  in  any  hopper  or  shoot 
without  an  efficient  exhaust  draught  and  air  guide,  so 
arranged  as  to  draw  the  dust  away  from  the  worker  as  near 
as  possible  to  the  point  of  origin." 

"  Every  person  employed  in  a  lead  process  shall  be 
examined  once  each  calendar  month  by  the  certifying  sur- 
geon of  the  district,  who  shall  have  power  to  suspend  from 
employment  in  any  lead  process." 

122 


WHITE  LEAD  MANUFACTURE  IN  EUROPE.  123 

"  Overalls  shall  be  provided  for  all  persons  employed  in 
lead  processes,  and  shall  be  washed  or  renewed  at  least  once 
every  week." 

"  No  person  shall  be  allowed  to  introduce,  keep,  prepare, 
or  partake  of  any  food,  drink  (other  than  medicines  pro- 
vided by  the  occupier  and  approved  by  the  certifying  sur- 
geon) or  tobacco  in  any  room  in  which  a  lead  process  is 
carried  on." 

141.  In   England,   the   majority   of   white   lead   plants 
operate  under  the  old  Dutch  process,  although  there  are 
one  or  two  plants  which  make  use  of  modifications  of  the 
German  Chamber  process,  which  process  will  be  discussed 
in   a  subsequent   portion   of   this   chapter.     The   Bischof 
process,  used  at  Mond's  Works  at  Brimsdown  in  Middlesex, 
has  recently  attracted  considerable  attention.     The  metallic 
lead  is  converted  into  an  oxide  by  a  simplified  process  and 
is  then  heated  to  250  to  300°  C.,  in  a  current  of  water  gas, 
which  reduces  the  lead  to  a  black  suboxide  of  unknown 
composition,  which  is  treated  with  water,  a  yellow  hydrate 
being  formed  and  considerable  heat  being  evolved.     The 
hydrate  is  then  converted  into  white  lead  by  treatment 
with  carbon  dioxide  gas. 

142.  English  Methods.     Many  of  the  details  of  the  old 
Dutch  process,  as  carried  out  by  the  English,  differ  con- 
siderably from  the  practice  in  this  country.     Instead  of 
using  round  buckles  and  placing  them  inside  of  the  corrod- 
ing pots,  the  more  usual  English  practice  is  to  cast  the  lead 
into  sheets  or  gratings,  which  are  laid  on  top  of  the  pots, 
which  are  much  smaller  than  those  in  use  in  this  country. 
The  building  of  the  stacks,  which  usually  have  a  height  of 
twenty-two  to  twenty-four  feet,  is  usually  done  by  women, 
who  work  barefoot,  and  who  convey  the  tan-bark  in  bas- 
kets carried  on  their  heads  (see  frontispiece).     The  lead  is 
usually  handled  by  cranes.     The  work  of  taking  down  the 


124 


THE  LEAD   AND   ZINC  PIGMENTS. 


WHITE  LEAD  MANUFACTURE  IN  EUROPE.  125 

stacks  is  performed  by  men  only,  who  wear  a  regulation 
costume  (see  Fig.  50),  required  by  the  Home-office  to 
be  worn  by  all  workers  in  the  white  lead  departments.  The 
white  lead  must  also  be  dampened  before  its  removal  from 
the  stack  rs  attempted.  This  is  in  marked  contrast  with 
the  practice  in  this  country,  where  any  sort  of  a  costume 
is  permitted,  and  in  the  several  factories  visited  by  the 
writer  no  attempt  was  made  to  keep  down  the  dust  in  the 
stack  operations. 

143.  Characteristics  of  English  White  Lead.     As  found 
on  the  market,  English  white  lead  in  oil  is  much  stiffer  than 
the  American  product;  this  is  due  to  the  different  method  of 
grinding,  where,  instead  of  rotary  buhrstone  mills,  powerful 
granite  rolls  moving  at  different  speeds  are  used.     The 
several  English  brands  examined  by  the  author  showed 
evidence  of  most  careful  corrosion,  resulting  in  great  purity 
of  color,  almost  theoretical  chemical  composition,  and  free- 
dom from  crystalline  or  sandy  lead.     Newcastle-on-Tyne 
is  one  of  the  principal  seats  of  manufacture.     Other  im- 
portant corroding  centers  are  London,  Glasgow,  Chester, 
Bristol  and  Sheffield. 

144.  German  Chamber  Process.     The  more  progressive 
German  manufacturers  use  a  modification  of  the  Dutch 
process,   which   materially   shortens   the   length   of   time 
required  by  the  other  process.     The  present  method  is 
probably  an  outgrowth  of  what  was  used  at  Klagenfurth,  in 
Carinthia,  for  a  great  many  years,  dating  back  perhaps  as 
far  as  1835.    White  lead  made  by  this  process  enjoyed  a 
remarkably  high  reputation.     This  presumably  was  due, 
not  so  much  to  the  method  of  manufacture,  as  to  the  very 
great  purity  of  the  lead  used,  which  was  produced  from  the 
mines  at  Bleiberg. 

145.  Klagenfurth  Modification.     The  principal  points  of 
difference  between  the  old  Dutch  process  and  the  Klagen- 


126 


THE   LEAD   AND   ZINC  PIGMENTS. 


WHITE  LEAD  MANUFACTURE  IN  EUROPE.  127 

furth  modification  consisted  in  the  vaporizing  of  the  vinegar 
or  acetic  acid  by  artificial  heat  and  the  production  of  the 
carbon  dioxide  by  the  fermentation  of  substances  other 
than  tan-bark  or  horse  manure,  usually  grape  skins  or 
refuse  from  wine  manufacture,  the  corrosion  being 
effected  in  large  closed  chambers  about  one  hundred  feet 
in  length,  each  chamber  being  divided  into  upper  and 
lower  compartments  by  a  loosely  constructed  floor,  through 
which  warm  air  from  below  could  readily  pass.  The  lower 
compartments  contained  the  furnace  with  flues  leading  to 
the  room  above.  On  the  floor  of  the  upper  compartment 
were  placed  strongly  constructed  boxes  containing  the 
acetic  acid  or  vinegar,  and  the  fermenting  material,  such 
as  grape  skins,  grape  pulp,  etc. 

146.  Above  each  box  was  a  framework  extending  to  the 
roof,  containing  numerous  cross  pieces,  over  which  the 
sheets  of  lead  were  placed.     The  warm  air  from  the  furnace 
below,  warming  the  contents  of  the  boxes,  not  only  vapo- 
rized the  acetic  acid,  but  also  effected  a  vigorous  fermen- 
tation of  the  grape  pulp,  liberating  considerable  amounts 
of   carbon  dioxide,  which,  with  the  water  vapor  arising 
with  the  acid,  afforded  all  the  requisites  of  the   Dutch 
process.      The  lead  being  cast  into  considerably  thinner 
sheets  than  was  customary  in  the  older  process,  and  with 
a  much  more  vigorous  action  of   the   corroding   agents 
resulted  in  the  shortening  of  the  time  of  corrosion  to  six 
or  eight  weeks.    The  resulting  white  lead,  after  being  freed 
from  metal  residues,  ground,  washed  and  dried,  afforded  a 
product  of  great  whiteness,  as  this  process  assured  entire 
absence  of  hydrogen  sulphide  with  the  attendant  blackening 
of  the  lead. 

147.  Present    German    Methods.   The    present    German 
chambers  process  may  be  regarded  as  the  result  of  the 
gradual   development   of   the    Klagenfurth    method,    the 


128  THE  LEAD  AND   ZINC  PIGMENTS. 

vaporization  of  the  acid  and  the  generation  of  the  carbon 
dioxide  being  under  direct  control  by  the  operator.  The 
corroding  rooms  or  stacks  are  approximately  thirty  feet 
long,  twenty  feet  wide  and  fifteen  feet  high,  the  walls 
being  covered  with  earthenware  tiles  for  resisting  the 
action  of  the  acid  vapors.  The  stacks  are  fitted  with 
racks  from  which  the  strips  of  cast  lead  are  hung  as  in  the 
Klagenfurth  process,  six  to  eight  tons  being  the  usual 
stack  charge. 

148.  The  acetic  acid  is  supplied  in  the  form  of  vapor 
by  evaporating  diluted  vinegar  in  iron  covered  pans  set 
in  brickwork,  the  vapors  being  conveyed  in  earthenware 
pipes  to  the  stacks  and  distributed  throughout  the  rooms 
by  means  of  large  perforated  pipes. 

The  carbon  dioxide  is  produced  by  burning  coke  or 
charcoal  in  iron  stoves,  care  being  taken  to  secure  as 
complete  combustion  as  possible,  the  resulting  gas  being 
introduced  into  the  stacks  through  the  perforated  pipes 
that  disseminate  the  acid  vapors,  thereby  securing  a  uni- 
form mixture  of  acid  and  gas. 

149.  Effecting  the  Corrosion.   The  formation  of  an  amor- 
phous  basic   carbonate   of   lead,   substantially   free   from 
neutral  carbonate  or  crystalline  carbonates,  by  the  chamber 
process  depends  on  the  formation  of  a  true  basic  acetate 
on  the  sheets  of  lead  before  the  conversion  into  carbonate 
is  begun.     In  order  to  secure  the  most  desirable  condi- 
tions, great  care  must  be  exercised  in  regulating  the  amounts 
and  strength  of  the  acid  admitted,  in  the  introduction  of 
proper   quantities  of  air,  and  in  maintaining  the  proper 
temperature  in  the  stack  room.     During  the  first  twenty- 
four  hours,  acetic  acid  of  five  to  six  per  cent  strength  may 
be  distilled  into  the  stack  room;  the  second  twenty-four 
hours  the  strength  should  be  reduced  to  about  one  per  cent, 
in  order  to  prevent  a  too  vigorous  action  on  the  lead  due 


WHITE  LEAD  MANUFACTURE  IN  EUROPE.  129 

to  the  increased  warmth  of  the  chamber.  On  the  third 
and  following  days  the  strength  of  the  acid  should  be 
further  reduced,  depending  on  the  conditions  observed  in 
the  stack.  0.5  to  0.7  per  cent  strength  represents  the  more 
usual  practice. 

150.  When  distinctly  perceptible  drops  of  dissolved  basic 
acetate  have  formed  on  the  lead  sheets,  carbon  dioxide 
should  be  admitted  and   the  supply  of  atmospheric  air 
reduced    correspondingly.     The    formation  of  white  lead 
proceeds  rapidly,  and  in  a  short  time  the  strips  of  lead  are 
covered  with  a  white  coating.     The  best  results  are  obtain- 
able  by  introducing  the   acetic   acid,   water  vapor,   and 
carbon  dioxide  in  such  amounts  as  will  maintain  a  damp 
or  slightly   pasty   feeling   to   this   coating,   necessitating 
entrance  to  the  chamber  at  regular  intervals,  which,  owing 
to  the  high  temperature,  often  60°  to  80°  C.,  will  require 
the  use  of  protective  clothing  and  a  means  of  artificial 
respiration  on  the  part  of  the  examiner. 

151.  Rapidity  of  Corrosion.   As  before  stated,  the  success 
of  the  operation  depends  on   the   formation  of  a  basic 
acetate  of  lead  first,  which  is  converted  into  basic  carbon- 
ate and  neutral  acetate  by  the  carbon  dioxide  and  air. 
The  neutral  acetate  reacts  in  turn  with  the  metallic  lead, 
forming  more  basic  acetate  with  the  assistance  of  the 
water  vapor,  which  is  converted  into  a  further  quantity 
of  white  lead  or  basic  carbonate  with  a  further  quantity 
of   carbon  dioxide,   more  neutral  acetate   being  formed. 
This  cyclic  reaction  explains  the  diminution  of  acetic  acid 
vapor  required  after  the  process  is  well  under  way. 

152.  The  corrosion  will  be  most  rapid  near  the  inlet 
openings  for  the  vapors  in  the  chamber  and,  therefore,  the 
action  will  be  completed  near  the  bottom  and  center  of  the 
room  before  the  strips  near  the  walls  and  upper  portion  of 
the  chamber  are  more  than  one-half  or  two-thirds  corroded; 


130  THE   LEAD   AND   ZINC  PIGMENTS. 

and,  in  order  to  secure  the  most  desirable  grade  of  white 
lead,  the  operation  is  stopped  before  complete  conversion  is 
secured  in  all  parts  of  the  chamber  in  order  to  avoid  over- 
corrosion,  entailing  conversion  into  crystalline  carbonates 
on  the  strips  most  vigorously  acted  upon.  Under  improved 
conditions  the  operation  requires  five  to  seven  weeks, 
eighty  to  ninety  per  cent  of  the  metallic  lead  being  con- 
verted into  white  lead.  The  crushing,  screening,  grinding 
and  washing  operations  are  entirely  similar  to  those  in  the 
old  Dutch  process. 

153.  Lack  of  Success   in  United  States.   Although  the 
chamber  process  has  been  very  successful  in  Germany  and 
in  the  adjoining  countries,  attempts  at  introduction  into 
the  United  States  have  failed  entirely.     Two  reasons  may 
be  assigned  for  this;  first,  lack  of  intimate  knowledge  on 
the  part  of  the  promoters  of  all  the  fine  points  to  be 
observed  in  controlling  the  corrosion,  resulting  in  a  product 
not  at  all  uniform  in  composition,  while,  on  the  other  hand, 
the  long  experience  of  the  German  chamber  manufacturers 
has  enabled  them  to  control  the  details  of  their  process 
successfully;  second,  lack  of  economy  of  the  chamber  pro- 
cess as  compared  with  the  Dutch  process  in  this  country, 
the  latter  undoubtedly  being  on  a  much  more  economical 
basis  here  than  in  Europe. 

154.  In    Montreal,    Canada,    a    white    lead    plant    has 
recently  been  built  which  operates  under  a  modified  form 
of  the  chamber  process,  and  as  there  is  only  one  other 
white  lead  in  Canada,  it  should  at  least  be  moderately 
successful. 

155.  The  French,  or  Thenard's  Process.   The  practica- 
bility of  this  process  was  first  demonstrated  about  1801 
by  Thenard,  a  French  chemist,  who  discovered  that  if 
carbon  dioxide  was  passed  into  a  saturated  solution  of 
basic  lead  acetate  that  white  lead  or  basic  carbonate  of 


WHITE  LEAD  MANUFACTURE  IN  EUROPE.  131 

lead  was  precipitated  and  a  certain  amount  of  neutral 
lead  was  regenerated  which  could  again  be  converted  into 
basic  acetate,  the  process  being  exemplified  by  the  follow- 
ing equations : 

2  PbO(litharge)  +Pb(C2H302)2  (lead  acetate) 

=  Pb(C2H302)2  •  2  Pb(OH)2  (basic  lead  acetate) 

3  Pb(C2H302)2  •  2  Pb(OH)2+4  C02 

=  2  [2  PbC03  •  Pb(OH)2]  (white  lead) 
+3  Pb(C2H302)2  (neutral  acetate)  +  4  H20 

156.  The  lead  acetate  may  be  obtained  by  treating 
granulated  lead  with  acetic  acid  in  the  presence  of  air  or 
by  treating  litharge  with  acetic  acid;  the  latter  method  is 
easier  and  more  rapid  but  the  higher  price  of  litharge 
offsets  these  advantages.  The  carbon  dioxide  must  be 
used  in  a  more  concentrated  state  than  in  the  chamber 
process  and  is  usually  prepared  by  heating  limestone  with 
burning  coke  in  a  specially  constructed  furnace  and  is 
forced  into  the  solution  of  basic  acetate  under  a  slight 
pressure.  The  precipitation  usually  requires  about  ten 
to  twelve  hours.  After  removal,  the  white  lead  is  washed 
thoroughly  to  free  it  from  acetate  salts.  The  product 
obtained  is  of  exceeding  whiteness,  but,  owing  to  a  some- 
what crystalline  nature,  has  less  opacity  or  hiding  power 
than  white  lead  made  by  the  other  processes.  For  this 
reason  and  because  of  the  comparatively  high  cost  of 
production,  this  process  has  not  come  into  the  general  use 
that  was  formerly  anticipated.  The  Matheson  process, 
which  is  a  much  improved  modification  of  the  Thenard 
principle,  is  the  only  one  of  this  type  in  successful  oper- 
ation in  this  country. 

157.  Present  French  Practice.  In  fact,  Thenard's  process 
has  practically  passed  out  of  use,  the  old  Dutch  process 
having  taken  its  place.  The  procedure  of  the  French,  old 


132  THE   LEAD   AND    ZINC   PIGMENTS. 

Dutch  process  corroders  is  very  similar  to  that  of  the  Eng- 
lish. In  some  factories  the  lead  is  cast  in  sheets  and  then 
rolled  into  a  spiral,  which  is  placed  inside  the  pot;  in  other 
works,  the  lead  is  cast  in  the  form  of  gratings  which  are 
placed  on  top  of  the  pots.  While  the  majority  of  French 
factories  have  discarded  manure  for  tan-bark,  a  number 
of  the  more  conservative  plants  still  depend  on  horse 
manure  as  the  source  of  heat  and  carbon  dioxide,  as  the 
corrosion  is  completed  in  nearly  half  the  time  required 
by  tan-bark.  The  grinding,  washing  and  drying  operations 
correspond  closely  with  the  English  practice. 


CHAPTER  XII. 

PROPERTIES  OF   WHITE  LEAD. 

158.  Composition.  White  lead  of  accepted  grade  is  a  white, 
earthy,  heavy  amorphous  powder  which  appears  under  the 
microscope  to  consist  of  round  globules  of  irregular  size. 
White  lead  prepared  by  the  newer  processes  is  usually 
whiter  than  that  made   by  the   Dutch   pro-  ~^ 
cess.                                                                           pb' 

159.  Chemically,  it  may  be  considered  as  a  >CO 
basic  carbonate  of  lead.     The  best  grades  of        Pb 
white  lead  approximate  very  closely  the  form-  >C03 
ula  2  PbC03 .  Pb(OH)2,  which  may  be  graphi-       Pb 
cally  represented  as  follows : 

According  to  this  formula,  there  are  about  sixty-nine 
parts  of  lead  carbonate  to  thirty-one  parts  lead  hydroxide. 
This  constitutes  an  increase  of  about  twenty-five  per  cent 
of  white  lead  on  the  basis  of  the  metallic  lead  used.  In 
other  words,  100  pounds  of  metallic  lead  produces  approxi- 
mately 125  pounds  of  white  lead.  There  are,  however, 
other  basic  carbonates  of  lead,  among  which  is  3  PbC03 . 
Pb(OH)2,  represented  by  the  graphic  formula: 

/OH 
Pb 

>C03 
Pb 

>C03 
Pb 

>C03 
Pb 

\OH 

133 


134  THE   LEAD   AND    ZINC  PIGMENTS. 

1 60.  The  Higher  Carbonates.   These  higher  carbonates 
increase  the  yield  of  white  lead,  and  there  is  a  notable 
tendency,  especially  with  the  newer  processes,  to  work  in 
this  direction,  as  the  added  increase  may  amount  to  from 
one  to  two  per  cent  of  the  weight  of  the  pig  lead  used. 
This  gain,  however,  is  at  the  expense  of  the  opacity,  as 
the  higher  carbonates  possess  less  hiding  power.     White 
lead  which  has  been  overcorroded  will  be  more  or  less  crys- 
talline instead  of  amorphous,  due  to  the  presence  of  the 
crystals  of  the  normal  carbonate.     Such  leads  are  markedly 
inferior  in  their  hiding  power. 

161.  Ageing  of  White  Lead.   The  ageing  of  white  lead, 
both  in  the  dry  state  and  in  oil,  has  been  a  fruitful  subject 
for  discussion.     As  to  the  precise  nature  of  the  changes 
undergone,  but  little  information  that  is  really  satisfactory 
is  obtainable.     That  certain  changes  take  place  in  both 
cases  is  undeniable,  as  an  experienced  painjber  can  almost 
invariably  pick  out  an  aged  lead  from  among  unaged  leads 
of  similar  manufacture.     The  author  has  observed  that  a 
tank  of  wet  white  lead  not  quite  up  to  standard  whiteness 
will,  on  standing  for  eight  to  ten  weeks,  improve  materi- 
ally   in    whiteness.     This    change    is    apparently   due    to 
molecular  rearrangements  tending  to  a  uniform  relation 
between  hydrate  and  carbonate,  and  is  apparently  assisted 
by  the  pressure  due  to  the  weight  of  the  contents  of  the 
tank. 

162.  Salvador!1   is   of   the   opinion   that   the   ordinary 
basic  carbonate  is  fully  as  stable,  if  not  more  so,  than  the 
normal  carbonate,  and  that  the  latter  is  easily  converted 
into  the  former  by  boiling  with  water  or  even  by  heating 
under  water  for  several  hours  at  70°  C.     It  is  certain, 
however,  that  under  other  circumstances  a  reverse  action 
will  take  place  resulting  in  the  formation  of  a  crystalline 

1  Gaz  Chim  Ital.  34,  87. 


PROPERTIES  OF  WHITE  LEAD. 


135 


FIG.  51.  —  OLD  DUTCH  PROCESS  WHITE  LEAD. 
Magnification  500  diameters. 


'-,0     '     }    r*<y         /*"  .        .       A'  ", 

,   ,.  .        •  •    -o,       ".-    •  *• 

••  r-      O*^ 


3^/  *••••;  •"*«!.  • 

"*   ,v  »  •';*>«•    '- 


FIG.  52.  —  MILD  PROCESS  WHITE  LEAD. 
Magnification  500  diameters. 


136 


THE   LEAD   AND   ZINC  PIGMENTS. 


normal  carbonate.  From  these  operations,  however,  and 
remembering  that  pressure  is  a  powerful  aid  to  chemical 
transformations,  it  is  not  at  all  strange  that  a  substance  of 
as  complex  a  nature  as  white  lead,  in  bulk  either  wet  or 
dry,  will  undergo  various  molecular  rearrangements  which 
an  ordinary  chemical  analysis  will  not  indicate. 

163.  Free  Fatty  Acids.   In  the  case  of  white  lead  ground 
in  oil,  the  problem  is  complicated  by  the  temperature  and 
pressure  of  grinding  and  the  amount  of  free  fatty  acids 
contained  in  the  linseed  oil.     Such  changes  as  will  occur 
under  these  conditions  will  reach  a  consummation  much 
more  rapidly,  probably,  than  in  the  previous  instances, 
and  these  changes  probably  terminate  within  a  few  weeks 
after  the  lead  has  been  ground. 

164.  Fineness  of  Particles.     White  lead  varies  greatly 
with  regard  to  the  fineness  of  the  particles  of  which  it  is 
composed.     Mild  process  white  lead  particles  are  uniformly 
fine,  while  old  Dutch  process  white  lead  is  composed  of 
fine  and  comparatively  coarse  particles  intimately  mixed. 
The  following  table  prepared  by  the  Paint  Manufacturers' 
Association,1  gives  some  idea  as  to  the  size  of  the  various 
pigment  particles  under  average  conditions  of  grinding. 


No. 

Name. 

Diameter  in  inches. 

Small. 

Average. 

Large. 

1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 

Dutch  process  lead  
Quick  process  lead 

.00002 
.00002 
.000014 
.00002 
.000014 
.00003 
.00006 
.00014 
.00003 
.00009 
.00015 

.00007 
.00012 
.00007 
.00007 
.00007 
.00007 
.00036 
.00044 
.00014 

.00026 
.00018 
.00014 
.00014 
.00014 

Picher  lead 

Zinc  oxide 

Zinc  lead                            .           •  • 

Beckton  white              

Barytes                       

.0021 
.0022 
.0003 
.025 
.49 

Gypsum               

Blanc  fixe             

China  clay 

Abestine 

First  Annual  Report,  Scientific  Section. 


PROPERTIES  OF  WHITE  LEAD. 


137 


FIG.  53.  —  PRECIPITATED  WHITE  LEAD. 
Magnification  500  diameters. 


FIG.  54.  —  SUBLIMED  WHITE  LEAD. 
Magnification  about  500  diameters. 


138  THE  LEAD   AND   ZINC  PIGMENTS. 

165.  Action  of  White  Lead  on  Linseed  Oil.     Much  has 
been  written  concerning  the  action  of  white  lead  on  linseed 
oil.     Hannay   and   Leighton,   in   the   Proceedings   of   the 
Chemical  Society,  No.  124,  have  questioned  the  frequently 
made  statement   "  that  saponification  takes  place  when 
white  lead  is  ground  with  linseed  oil,  giving  rise  to  peculiar 
working  properties,  which  other  pigments  do  not  have. 
They  show  that  no  such  combination  between  the  lead  and 
oil  takes  place,  and  that  a  very  small  trace  of  oleate  of  lead 
in  the  oil  will  cause  serious  blackening  under  the  influence 
of  the  small  amount  of  sulphuretted  hydrogen  in  the  air, 
when  pure  white  lead  would  hold  its  color,  showing  that 
such  saponification  would  be  decidedly  deleterious." 

1 66.  The  conclusion  drawn  was  that  dry  white  lead 
produced  slow  oxidization,  but  no  saponification  of  the  oil, 
since  saponification  implied  hydrolysis,   and   could  only 
take  place  in  the  presence  of  moisture. 

A.  H.  Hooker  confirms  these  statements,  and  calls  atten- 
tion that  "  in  wet  or  pulp  ground  leads  alone  we  find 
a  partial  saponification  to  take  place  and  that  such  lead 
is  vastly  more  susceptible  to  the  blackening  influence  of 
sulphuretted  hydrogen  than  ordinary  lead." 

167.  Stability  of  White  Lead  toward  Heat.     White  lead 
is  riot  a  very  stable  pigment.     It  begins  to  lose  its  com- 
bined water  at  110  to  130°  C.     Several  of  the  quick-process 
leads  break  down  much  more  easily  than  old  Dutch  process 
lead.     By  keeping  the  temperature  below  150°  C.,  all  of  the 
combined  water  can  be  driven  off  in  six  to  eight  hours,  with 
very  slight  loss  of  carbon  dioxide. 

1 68.  A  slightly  higher  heat  breaks  down  the  white  lead 
at  once  into  an  oxide,  high  temperature  giving  litharge, 
and  a  continued  lower  temperature  an  oxide  which  absorbs 
oxygen,  forming  the  product  known  as  orange  mineral, 
which  may  be  considered  a  debased  form  of  red  lead.     In 


PROPERTIES  OF  WHITE  LEAD.  139 

actual  practice  the  crystalline  tailings  or  sandy  lead  is 
largely  used  for  this  purpose. 

169.  Reactions  with  Acids.   Owing  to  the  weakness  of  the 
chemical  linkage  between  radicals  composing  white  lead,  it 
is  extremely  susceptible  toward  acids  and  alkalies,  being 
readily  soluble  in  acetic  and  nitric  acids,  and  hot  hydro- 
chloric acid,  the  lead  chloride  formed  separating  out  on 
cooling.     Hence  when  hydrochloric  acid  is  used  as  a  sol- 
vent for  lead  compounds  in  mixtures,  such  solutions  should 
be  filtered  boiling  hot,  else  crystals  of  lead  chloride  will 
form  in  the  pores  of  the  filter  paper,  which  will  be  dissolved 
out  with  difficulty,  even  with  boiling  water.     Sulphuric 
acid  converts  lead  compounds  into  an  insoluble  sulphate. 
This  operation  is  much  made  use  of  in  the  quantitative 
analysis  of  lead  compounds.     However,  in  the  presence  of 
even  slight  amounts  of  nitric,  hydrochloric  or  acetic  acids 
the  lead  sulphate  is  sufficiently  soluble  to  introduce  quite  a 
serious  error  in  the  determination.     The  addition  of  alcohol 
will   overcome   this   difficulty   to   a   considerable   extent, 
although  it  is  best  to  expel  any  free  nitric,  acetic,  or  hydro- 
chloric acid  by  evaporation. 

170.  Solubility.     Solubility  of  lead  compounds  in  100  c.c. 
pure  water  at  room  temperature: 

Compound.  Grams  Soluble. 

Lead  Carbonate 0 . 00011 

Lead  Sulphate 0.00410 

Lead  Chromate 0.00002 

Lead  Chloride 1.08 

Lead  Acetate 50.0 

Lead  Nitrate 56.0 

171.  Action  of  Sulphur  Compounds.     As  is  well  known, 
white  lead  is  easily  attacked  by  sulphuretted  hydrogen  and 
gases  containing  sulphur  compounds,  pulp  ground  leads 
being  more  susceptible  than  leads  previously  freed  from 


140  THE  LEAD  AND   ZINC  PIGMENTS. 

water  before  being  ground  in  oil.  This  blackening  or 
darkening  is  one  of  the  leading  objections  to  its  use  as  the 
base  of  white  paints.  In  fact,  for  interior  work,  but  little 
strictly  pure  lead  is  used ;  generally  a  mixture  of  zinc  oxide 
and  white  lead  is  used,  in  which  the  zinc  oxide  is  in  pre- 
ponderance, as  the  effect  of  sulphur  compounds  on  zinc 
oxide  is  not  noticeable,  zinc  sulphide  being  white.  In 
cities  where  large  quantities  of  soft  coal  are  burned,  the 
darkening  of  white  lead  is  especially  rapid.  This  is  due 
not  only  to  the  sulphurous  gases  in  the  atmosphere,  but 
also  to  the  soot  particles  which  lodge  on  the  comparatively 
rough  surface  of  the  lead  paint  film,  and  through  the  agency 
of  moisture,  the  sulphur  and  other  corrosive  substances  in 
the  soot  act  directly  on  the  paint  film. 

172.  Chalking  of  White  Lead.  The  principal  objection 
brought  against  white  lead  as  a  paint  pigment  is  that  it 
"  chalks  or  flours."  This  chalking  may  begin  within  four 
months  after  application  or  may  not  be  apparent  at  the  end 
of  twelve  to  fifteen  months.  Many  reasons  have  been 
ascribed  for  this  defect,  for  defect  it  is,  of  white  lead.  In 
many  instances  the  oil  is  undoubtedly  at  fault,  especially 
oils  which  either  by  treatment  or  long  standing  have 
become  high  in  free  fatty  acids,  and  will  cause  a  rapid  dis- 
integration of  the  paint  film.  Again,  the  temperature  at 
which  the  lead  is  ground  in  the  mill  has  much  to  do  with 
its  chalking.  The  low  temperature  at  which  white  lead 
begins  to  break  down  certainly  renders  any  undue  heating 
of  the  mill  a  serious  consideration.  Many  grinders  even 
to-day  are  using  uncooled  buhr  mills.  Even  with  a  water- 
cooled  mill  operated  as  efficiently  as  possible,  it  is  often 
difficult  to  keep  below  the  danger  temperature,  especially 
after  the  mills  have  been  running  six  or  seven  hours.  In 
many  instances  the  result  is  so  pronounced  that  the  lead 
hardens  in  the  package  within  36  hours  after  grinding. 


PROPERTIES  OF  WHITE  LEAD.  141 

173.  Effect   of   Residual  Acetates.     Another  important 
cause  of  chalking,  and  one  that  the  author  believes  should 
merit  special  attention  on  the  part  of  chemists,  is  the  pres- 
ence in  greater  or  less  quantity  of  acetate  of  lead,  which  is 
to  be  found  in  all  white  leads  made  through  the  instru- 
mentality of  acetic  acid.     In  numerous  tests  which  have 
come  under  the  observation  of  the  writer,  white  leads  pre- 
pared without  the  use  of  acetic  acid  "  chalk  "  very  much 
slower,  and  to  a  much  less  extent  than  the  other  leads. 
That  these  more  or  less  basic  acetates  of  lead  exert  an  influ- 
ence all  out  of  proportion  to  the  amount  present  seems 
certain.     In  fact  their  action  may  be  regarded  as  of  a  cata- 
lytic nature,  and  the  author  is  firmly  convinced  that  many 
abnormal  cases  of  u  chalking,"  if  carefully  traced,  would 
have  shown  the  presence  of  an  abnormal  quantity  of  acetate 
of  lead  present  in  the  white  lead  used. 

174.  Protracted  Oxidation.     It  is  also  a  well-known  fact, 
as  Hooker  states,  "  that  white  lead    promotes   the   slow 
oxidization  or  drying  of  the  oil  and  the  ultimate  product 
of  this  oxidization  is  a  dry  powder  without  life  or  elasticity. 
White  lead  hastens  this  end  of  completed  drying  much  more 
rapidly  than  any  other  pigment,  except  of  course  red  lead 
and  litharge,  and  so  unless  some  means  is  used  to  retard 
the  action,  the  oil  perishes  and  the  dry  lead  alone  is  left 
to  wash  or  chalk  off.     However,  the  chalking  of  white 
lead  while  objectionable  is  not  entirely  so,  since  it  leaves 
the  surface  in  an  excellent  condition  to  receive  a  fresh  coat 
of  paint." 

175.  White  Lead  Specifications.   One  of  the  best  speci- 
fications that   has   come   under   the  observation   of   the 
author  covering  the  use  of  white  lead  is  the  one  in  use 
by  the   Rock   Island   Lines   of   the   St.   Louis   and    San 
Francisco  Railroad  Company.    The  following  are  the  points 
covered : 


142  THE   LEAD   AND    ZINC   PIGMENTS. 

176.  "  Material.   White  lead  must  be  furnished  in  paste 
form  and  must  contain  nothing  but  oil  and  pigment,  in 
the  following  proportions  by  weight: 

Oil,  not  less  than  7  per  cent  nor  over  10  per  cent. 
Pigment,  not  less  than  90  per  cent  nor  over  93  per  cent, 

the  paste  to  contain  not  over  one  per  cent  by  weight  of 
volatile  matter,  at  212°  F.,  and  must  be  free  from  skins 
and  mix  readily  for  spreading,  and  when  made  into  a  paint 
it  must  not  be  deficient  in  opacity,  and  must  be  of  maxi- 
mum whiteness,  work  freely  under  the  brush,  and  when 
thinned  down  ready  to  use  it  must  not  settle  into  a  hard 
mass  on  standing  overnight." 

177.  "  Oil.   The  pigment  must  be  ground  in  pure  linseed 
oil,  well  clarified  by  settling  and  age,  and  must  otherwise 
meet  the  requirements  of  this  company's  standard  speci- 
fication for  raw  linseed  oil. 

"  Pigment.  The  pigment  desired  is  the  pure,  fully- 
hydrated  basic  carbonate  of  lead,  which  must  not  be 
crystalline  in  structure  or  contain  more  than  0.15  per  cent 
acetic  acid,  and  must  approach  closely  the  following  com- 
position : 

Lead  carbonate,  not  less  than  67  per  cent  nor  over 

80  per  cent. 

Lead  hydrate,  not  less  than   20   per  cent  nor  over 
33  per  cent. 

"The  pigment  must  not  contain  more  than  one-half  of 
one  per  cent  of  lead  sulphate." 

178.  The  only  objection  the  writer  would  raise  against 
these  requirements  is  the  high  per  cent  of,  carbonate  per- 
mitted.    Seventy-six  per  cent  should  be  regarded  as  the 
highest  desirable   amount,    as  above  this  point  the  lead 
begins  to  lose  in  opaqueness  or  body. 


CHAPTER  XIII. 

LEAD   POISONING. 

179.  The  English  White  Lead  Commission.    In  England, 
and  also  on  the  continent,  especially  in  France,  there  has 
been  a  very  pronounced  agitation  against  the  manufacture 
and  use   of   white  lead   as  a  paint  pigment,  due  to  the 
alleged  harmful  effect  on  the  employees  of  the  white  lead 
works  and  the  painters  who  use  the  product.     This  agita- 
tion led  to  the  formation  of  the  White  Lead  Commission 
in  England,  in  1898,  whose  report  was  instrumental  in 
introducing    many    improvements    in    the    industry.     In 
France  the  white  lead  industry  has  been  made  the  object 
of  special  legislation  restricting  and  regulating  the  sale 
and  use  of  white  lead. 

180.  Lead   Poisoning  in  United  States.    In  the  United 
States  the  question  of  white  lead  poisoning  has  remained 
practically   unnoticed.     To    the   casual   reader   this   may 
seem  strange,  but  when  we  compare  the  condition  of  the 
industry  abroad   and    at    home,   the  reasons  why  it  has 
attracted  so  slight  attention  at  once  becomes  apparent. 

Two  reasons  primarily  may  be  advanced  as  an  explana- 
tion for  this  state  of  affairs : 

1.  Superiority  of  American  methods  and  workmen. 

2.  Absence  of  female  labor  in  this  industry  in  America. 

181.  In  the  United  States  the  white  lead,  after  having 
been  ground  in  the  water  mills  and  subjected  to  the  usual 
washing,  is  pumped  on  large  copper  steam-heated  drying 
pans,  some  of  which  are  nearly  one  hundred  feet  in  length 
by  nearly  ten  or  more  feet  in  breadth,  while  in  England 

143 


144  THE   LEAD   AND   ZINC  PIGMENTS. 

until  very  recently  the  thick  paste  was  placed  in  large 
earthenware  bowls  which  were  carried  by  women  to  drying 
compartments  known  as  "  stoves,"  which  were  essentially 
rooms  heated  by  a  stove  or  steam  coils  and  provided  with 
a  large  number  of  shelves  arranged  around  the  sides. 
Until  1898,  the  "  filling  "  and  "  drawing  "  of  the  stoves 
was  very  largely  done  by  women,  and,  as  Sir  Thomas  Oliver1 
has  pointed  out,  this  part  of  the  process  "  has  been  the 
cause  of  a  larger  number  of  severe  and  fatal  cases  of  lead 
poisoning  than  any  other  department  in  a  white  lead 
factory."  "  The  work  was  found  to  be  so  detrimental  to 
female  life  that  the  White  Lead  Commission  recommended 
that  no  woman  or  girl  should  be  allowed  to  work  in  the 
stoves."  At  the  present  time  while  the  use  of  copper  dry- 
ing pans  is  becoming  more  common  in  England  and  on  the 
continent,  the  practice  has  by  no  means  become  universal. 

182.  English  Regulations.   In  1899,  the  Chief  Inspector 
of  Factories  issued  special  rules  for  white  lead  works.     These 
were  modified  again  slightly  in  1901,  and  the  following  are 
the  essential  requirements  as  stated  in  Factory  Acts  of 
1901. 

183.  Duties  of  Occupiers.    1.   No  person  shall  be  em- 
ployed in  drawing  Dutch  stoves  on  more  than  two  days 
per  week. 

2.  No  woman  shall  be  employed  or  allowed  in  the  white 
beds,  rollers,  washbecks,  or  stoves,  or  in  any  place  where 
dry  white  lead  is  packed,  or  in  other  work  exposing  her 
to  white  lead  dust. 

3.  The  occupier  shall  provide  and  maintain  sufficient 
and  suitable  respirators,  overalls  and  head  coverings,  and 
shall  cause  the  same  to  be  worn. 

4.  A  supply  of  a  suitable  sanitary  drink,  to  be  approved  by 
the  appointed  surgeon,  shall  be  kept  for  the  use  of  the  workers. 

1  Dangerous  Trades,  page  289. 


LEAD  POISONING. 


145 


FIG.  55.  —  REQUIRED  COSTUME  OF  ENGLISH  WHITE  LEAD  WORKER. 


146  THE   LEAD   AND   ZINC  PIGMENTS. 

5.  The  occupiers  shall  provide  and  maintain  lavatories 
for  the  use  of  workers,  one  lavatory  basin  for  every  five 
persons  employed,  to  which  must  be  supplied  a  constant 
supply  of  hot  and  cold  water. 

6.  Before  each  meal,  and  before  the  end  of  the  day's 
work,  at  least  ten  minutes  in  addition  to  the  regular  meal 
times  should  be  allowed  to  each  worker  for  washing. 

7.  The  occupier  shall  provide  and  maintain  sufficient 
baths  and  dressing-rooms  for  all  persons  employed  in  lead 
processes,  with  hot  and  cold  water,  soap,  and  towels,  and 
shall  cause  each  such  person  to  take  a  bath  once  a  week 
at  the  factory.     A  bath  register  shall  be  kept  containing  a 
list  of  all  persons  employed  in  lead  processes,  and  an  entry 
of  the  date  when  each  person  takes  a  bath. 

184.  Duties  of  Persons  Employed  (Briefly  Stated).    1.   No 
person,  after  suspension  by  the  appointed  surgeon,  shall 
work  in  a  lead  process  without  his  written  sanction. 

2.  Every  person  employed  in  a  lead  process  shall  take 
a  bath  at  the  factory  at  least  once  a  week,  and  wash  in  the 
lavatory  before  bathing;  having  done  so,  he  shall  at  once 
sign  his  name  in  the  bath  register  with  the  date. 

3.  No  person  employed  in  a  lead  process  shall  smoke 
or  use  tobacco  in  any  form  or  partake  of  food  or  drink 
elsewhere  than  in  the  dining-room. 

4.  No  person  shall  obtain  employment  under  an  assumed 
name,  or  under  any  false  pretenses. 

185.  English  Statistics.  That  these  regulations  adopted 
in  1899  were  justified  is  amply  shown  by  the  official  reports 
on  lead  poisoning  for  the  three  years  preceding. 

Year.  Cases. 

1896  357 

1897  370 

1898  480 


LEAD  POISONING.  147 

These  figures  indicate  that  one  in  every  seven  to  eight 
employees  suffered  from  lead  poisoning.  The  drying 
stoves  furnished  two  and  one-half  times  as  many  cases 
of  plumbism  as  the  corroding  beds. 

186.  Precautions    Adopted    by    the    French.    In    France 
even  more  rigid  precautions  are  prescribed  against  lead 
poisoning  than  in  England.     Those  in  use  at  the  corrod- 
ing works  of  M.  Expert-Besangon  may  be  taken  as  repre- 
sentative of  the  care  exercised  with  French  white  lead 
workers.    As  the  best  preventative  of  plumbism,  regular 
rations  of  milk  are  prescribed   which  the  workmen   are 
required  to  take  at  six  o'clock  and  nine  o'clock  in  the 
morning  and  three  o'clock  in  the  afternoon.    To  the  nine 
o'clock  ration  is  added  hyposulphite  of  soda,  about  one  and 
a  half  pounds  to  the  gallon.     It  is  also  to  be  noted  that  the 
workmen  are  not  permitted  to  drink  their  milk  or  partake 
of  food  in  any  of  the  rooms  where  any  lead  products  are 
handled  or  are  in  process.     The  men  are  required  to  wash 
their  face  and  hands  and  rinse  out  their  mouths  before 
eating  or  drinking  their  milk  and  on  leaving  the  factory 
at  the  close  of  the  day.     Frequent  baths  are  also  required. 
The  time  required  for  all  of  these  operations  is  considered 
a  part  of  the  day's  work  and  for  which  the  workmen  are 
paid. 

187.  As  a  final  precaution  each  workman  is  inspected 
at  least  once  a  week  by  a  doctor  who  keeps  a  complete 
record  of  the  health  of  each  man.     When  indications  of 
lead  poisoning  are  observed,  cessation  from  work  is  ordered 
by  the  doctor  until  recovery  is  complete,  at  which  time  a 
certificate  is  issued  permitting  him  to  return  to  work. 

188.  Recent  Improvements.   Since  1901,  conditions  have 
materially  improved  in  England,   as  in   1900  the    total 
cases  notified  in  the  Northeastern    Division  of    England 
was  197,  in  1901  there  were  98  cases  notified,  and  in  1902 


148  THE   LEAD   AND   ZINC  PIGMENTS. 

only  69  cases  were  notified.  On  the  Continent  methods 
have  been  introduced  to  some  extent  for  incorporating  the 
lead  with  oil  without  drying  out  the  water,  similar  in  prin- 
ciple to  the  white  lead  pulping  mills  used  in  this  country, 
thus  avoiding  danger  from  white  lead  dust  common  to 
this  part  of  the  process.  In  this  country  mechanical 
barrel  packers  and  the  strict  use  of  respirators  have  reduced 
this  danger  to  a  minimum,  there  being  much  more  lead 
sold  dry  than  abroad. 

189.  The  taking  down  of  the  corroding  beds  is  perhaps 
the  most  dangerous  part  of  the  process  in  this  country,  as 
it  is  an  operation  in  which  manual  labor  cannot  with  ad- 
vantage be  supplanted  by  mechanical  devices.     The  incor- 
poration of  the  dry  lead  oil  by  means  of  "  chasers"  is  also 
a  serious  source  of  lead  poisoning,  unless,  as  is  the  practice 
in  some  plants  of  placing  the  chasers  in  small  rooms,  the 
workmen  remaining  outside  until  the  incorporation  of  the 
lead  and  oil  is  complete. 

190.  Restrictive  Legislation.     Even  when  all  reasonable 
precautions  have  been  adopted,  there  is  always  danger  of 
the   employees   acquiring  lead   poisoning  in   a  corroding 
plant,  especially  one  in  which  the  old  Dutch  process  is  used, 
but  in  the  opinion  of  the  writer  the  danger  is  not  nearly 
serious  enough  to  warrant  restriction  by  legislation  against 
the  manufacture  and  use  of  white  lead.     While  it  is  true 
that  painters  suffer  more  or  less  from  lead  poisoning,  it  is 
usually  due  to  lack  of  even  ordinary  cleanliness,  for  the 
painter  who  is  scrupulously  neat  is  very  seldom  affected. 
Much  of  the  complaint  regarding  the  various   forms  of 
kidney  diseases  with  which  many  painters  are  troubled, 
especially   those  working  under  cover,  is   due   essentially 
to  the  irritating  and  toxic  effect  of  the  turpentine  used. 
Carriage    painters    are    perhaps    more    seriously    affected 
by  this  class  of  troubles  than  any  others,  and  yet  the 


LEAD  POISONING.  149 

amount  of  white  lead  applied  by  them  is  very  small  as 
compared  with  the  amount  applied  by  the  ordinary  house 
painter. 

191.  Danger  to  Women.     The  different  forms  and  mani- 
festations of  lead  poisoning,  such  as  "  wrist  drop/'  "  lead 
colic/'  are  more  or  less  well  known,  but  the  more  serious 
aspects  which  this  affliction  may  assume  should  be  more 
generally  known  and  recognized,  and  effectual  measures 
taken  to  prevent  development  into  a  chronic  or  acute  stage. 
The  effect  of  lead  poisoning  is  very  much  more  serious  on 
women  than  on  men.     This  has  been  amply  demonstrated 
by  Oliver/  who  states  that  "  where  the  two  sexes  are  as 
far  as  possible  equally  exposed  to  the  influence  of  lead, 
women    probably    suffer    more    rapidly,    certainly    more 
severely,  than  men."     "  Children  of  female  lead  workers 
almost  invariably  die  of  convulsions  shortly  after  birth  or 
during  the  first  twelve  months.     If  the  child  is  the  offspring 
of  parents  both  of  whom  are  lead  workers,  it  is  puny  ami 
ill  nourished,  and  is  either  born  dead,  or  dies  a  few  hours 
after  birth."     Fortunately  in  this  country  female  labor  is 
not  employed  in  white  lead  factories. 

192.  Symptoms  of  Lead  Poisoning.     In  discussing  white 
lead  poisoning,  Oliver  states  in  the  same  connection,  that : 
"  The  symptoms  of  plumbism  are  manifold.     Usually  easy 
of  recognition,  they  are  sometimes  so  obscure  as  to  render 
the  malady  difficult  of  detection,  even  by  a  careful  physi- 
cian.   One  of  the  earliest  signs  is  pallor  of  the  countenance. 
There  is  developed  a  degree  of  anaemia  which  gradually 
increases  until  the  features  become  altered  and  expression- 
less, a  form  of  bloodlessness  which,  since  it  is  characteristic 
of  lead  poisoning,  is  spoken  of  as  Saturnine  cachexia.     This 
becomes  very  pronounced,  so  that  it  is  easy  to  recognize 
lead  workers  by  sight.    A  few  weeks'  work  will  transform  a 

1  Dangerous  Trades,  pages  301,  303. 


150  THE   LEAD   AND    ZINC  PIGMENTS. 

healthy-looking,  florid  young  woman  or  man  into  a  pallid 
and  listless  individual.  During  the  time  that  the  pallor  is 
developing,  the  individual  often  complains  of  a  disagree- 
able metallic  taste  in  the  mouth,  especially  on  rising  in  the 
morning,  and  of  a  distaste  for  food." 

193.  "  The  reason  why  colic  is  such  a  common  and  early 
symptom  of  saturnine  poisoning  is  because  the  alimentary 
canal  is  one  of  the  principal  channels  by  which  lead  enters 
the  system,  and  lead  is  known  to  have  a  special  affinity  for 
muscular  fiber  and  nerve  tissue,  and  to  induce  spasms. 
Colic  is  often  attended  by  vomiting  and  by  obstinate  con- 
stipation.    The   pain  is   of  varying  degrees   of   severity. 
Sometimes  it  is  so  mild  that  the  individual  is  able  to  follow 
his  occupation,  but  in  discomfort.     At  other  times  it  is  so 
severe  that  he  rolls  about  in  agony,  and  is  with  difficulty 
kept  in  bed.     After  recovery  most  of  those  who  have  been 
ill  return  too  early  to  employment.     One  attack  of  plumb- 
ism  unfortunately  predisposes  to  another.     On  examining 
the  mouth  of  a  lead  worker  there  is  usually  to  be  seen  a 
bluish  line  along  the  margin  of  the  gums  close  to  the  teeth. 
The  gums  are  ulcerated,  and  in  the  case  of  an  old  lead 
worker  they  are  retracted,  and  thus  expose  a  considerable 
length  of  the  fang." 

194.  Effect  on  Nervous  System.     It  is  upon  the  nervous 
system  that  the  worst  effects  of  lead  are  seen.     Usually 
after  having  experienced  one  or  more  attacks  of  colic,  but 
sometimes  without  these,  a  lead  worker  suddenly  or  grad- 
ually loses  power  in  his  hands  and  fingers.     His  hands 
become  paralyzed,  hang  powerless  by  his  side,  and  the 
patient  is  said  to  be  suffering  from  "  wrist  drop."     In 
"  wrist  drop"   the  extensor  muscles  of  the  fingers  and 
wrists  rapidly  waste.     As  a  rule,  the  affection  is  painless, 
but  in  some  instances  the  loss  of   power  is  preceded  by 
muscular  tenderness.     The  muscles  of  the  shoulders  and 


LEAD  POISONING.  151 

upper  arm,  too,  may  be  affected,  or  the  weakness  affects 
the  muscles  of  the  foot,  and  causes  "  ankle  drop." 

195.  Chronic  Lead  Poisoning.   There   still   remains   the 
chronic  type  of  lead  poisoning  "  in  which  the  individual, 
after  having  been  exposed  for  a  lengthened  period  to  the 
influence  of  lead,   and  having  experienced  one  or  more 
attacks  of  colic,  indicating  that  his  system  is  becoming 
impregnated  with  lead,  is  never  well;  he  is  profoundly 
anaemic,  is  the  subject  of  frequent   headache,   imperfect 
vision,  and  incomplete  wrist  drop.    Albumen  is  present  in 
the  urine,  and  there  is  a  slight'degree  of  dropsy  of  the  face, 
hands,  and  feet,  —  physical  signs  that  point  with  these  just 
mentioned  to  structural  alterations  having  occurred  in  the 
kidneys,  liver,  heart,  and  blood-vessels,  retina  and  nervous 
system.     Life  drags  on  from  day  to  day,  only  to  end  in  a 
lingering  illness,  or  it  is  brought  to  a  sudden  close  either 
by  ur»mic  convulsions,  or  in  consequence  of  rupture  of  a 
blood-vessel  in  the  brain." 

196.  Absorption    Through    the    Skin.    Many    authorities 
consider  that  the  inhalation  of   lead   dust   or   its   intro- 
duction into  the  system  through  the  mouth  is  far  more 
dangerous  than  ordinary  contact  with  the  skin,  as,  for 
example,    the    hands    and    arms.     The  author,   however, 
believes  that  the  danger  of  absorption  through  the  skin  has 
been  much  underestimated.     In  one  corroding  plant  with 
which  the  author  was  intimately  acquainted,  over  twenty- 
five  per  cent  of  its  workmen  in  one  year  received  medical 
treatment  for  lead  poisoning,  the  large  majority  of  whom 
never  came  in  contact  with  any  perceptible  amount  of 
lead  dust;  and  as  they  were  required  to  wash  thoroughly 
before  eating,  the  amount  introduced  through  the  mouth 
was  very  slight.     The  liberal  use  of  heavy  paraffine  oil  on 
the  hands  and  arms  did  much  to  alleviate  the  absorption, 
and  immediate  improvement  was  noticed. 


CHAPTER  XIV. 

MANUFACTURE  OF   ZINC   OXIDE. 

197.  Ancient  History.   This  pigment  which  occupies  such 
a  prominent  position  in  the  paint  world  to-day  was  practi- 
cally an  unknown  paint  material  sixty  years  ago.     Yet, 
while  its  rise  into  favor  has  been  so  rapid  and  recent,  it 
has  been  known  to  scientists  for  many  hundred  of  years. 
In  fact,  its  history  extends  as  far  back  as  that  of  white  lead, 
for  Pliny  mentions  it  under  the  name  of  cadmia  when 
describing  the  sublimate  of  impure  zinc  oxide  found  in  the 
chimneys  of  the  brass  foundry  furnaces.     Discorides  also 
states   that  in  the  manufacture  of  brass  "  pomphlox  is 
formed  like  tufts  of  wool."    The  later  alchemists  spoke 
of   this    characteristic    formation   of   zinc   oxide   as   lana 
philosophica.      The  similarity  between  the  oxide  of  zinc, 
obtained  by  the  combustion  of  metallic  zinc,  and  snow  led 
the  alchemists  to  name  it  nix  alba. 

198.  Production  on  a  Commercial  Scale.   Unlike  white 
lead,   zinc  oxide  was  of  little  or  no  practical  use  to  the 
ancients,  and   the  industry   remained   undeveloped.     One 
of  the  first  suggestions  as  to  its  adaptability  as  a  paint 
pigment  was  made  in  1781  by  a  French  chemist,  who 
discovered  the  process  of  converting  zinc  into  oxide  on  a 
commercial  scale,  and  advised  its  use  instead  of  white  lead, 
but  with  no  especial  results.    And  it  was  not  until  the 
time  of  LeClaire  the  famous  French  contractor  and  painter 
in  1847  that  zinc  oxide  came  into  commercial  use  as  a 
pigment. 

199.  Work  of  LeClaire.   LeClaire,  wiser  than  the  major- 

152 


MANUFACTURE  OF  ZINC  OXIDE.  153 

ity  of  reformers,  turned  public  prejudice  against  itself. 
His  contracts  called  for  the  use  of  pure  white  lead,  and 
while  he  believed  in  the  superiority  of  zinc  oxide  he  recog- 
nized the  futility  of  attempting  to  convince  the  public  by 
any  ordinary  means.  He  therefore  interpreted  his  con- 
tracts rather  liberally,  and  used  zinc  oxide  instead  of  white 
lead.  "  The  superior  beauty  and  durability  of  his  work 
rapidly  increased  his  trade,  and  when  he  felt  his  position 
sufficiently  strong,  he  turned  the  prejudice  of  his  patrons 
against  themselves  by  painting  here  and  there  in  each  new 
building  a  certain  section  with  pure  lead.  At  the  end  of 
a  short  period  the  lead  naturally  began  to  change  color 
and  to  '  chalk  off/  and  the  inferiority  of  these  portions 
promptly  attacked  criticism.  When  LeClaire  was  ready, 
he  proclaimed  the  facts,  with  the  final  result  that  to-day 
zinc  holds  an  absolutely  unassailable  position  in  France. 
LeClaire  received  honors  and  medals  in  profusion,  and  the 
government  conferred  upon  him  the  order  of  the  Legion 
of  Honor." 

200.  LeClaire 's  Process.  The  LeClaire  process  of  manu- 
facturing zinc  oxide  consisted  of  volatilizing  the  metallic 
zinc  in  a  retort,  the  resulting  zinc  vapors  being  mingled 
with  currents  of  air  and  burned,  the  zinc  converted  into  the 
oxide  which  was  collected  as  a  white  powder  in  a  series  of 
flues  and  chambers;  his  process  being  the  precursor  of  the 
present   "  French  Process/'     The   factory  of   LeClaire  is 
still  in  operation.     The  high  cost  of  the  product  prevented 
its  coming  into  general  use  until  after  the  elaborate  investi- 
gations of  the  French  Government  which  resulted  in  its 
being  required  in  all  government  work. 

201.  Present  French  Process.   The  Societe  Anonyme  de 
la  Vielle  Montagne  is  the  largest  producer  of  zinc  oxide  by 
the  French  process  in  Europe,  producing  in  the  neighbor- 
hood   of    8000    metric    tons   yearly,   equivalent    to    8820 


154  THE  LEAD   AND   ZINC  PIGMENTS. 

English  tons.  The  metallic  zinc  or  spelter  is  volatilized  in  a 
special  form  of  retort;  the  vapor  issuing  from  the  retort  is 
oxidized  in  the  presence  of  a  current  of  air,  and  after  passing 
through  a  series  of  pipes  is  collected  in  long  settling  cham- 
bers provided  with  hopper  bottoms  through  which  the 
collected  oxide  may  be  removed.  The  purity  of  the  oxide, 
especially  as  regards  whiteness,  depends  much  upon  the 
distance  it  is  carried  in  the  settling  chambers  before  deposi- 
tion, and  the  product  is  graded  accordingly;  the  two  lead- 
ing brands  being  Vielle  Montagne  Green  Seal  and  Red  Seal, 
the  former  being  the  better  quality  and  commanding  the 
higher  price. 

202.  Composition.   The  composition  of  the  Vielle  Mon- 
tagne zinc  oxides  varies  according  to  Ingalls  as  follows : 

Zinc  oxide 99.695  to  99.995  per  cent 

Lead  oxide 0.200  to       .002  per  cent 

Cadmium  oxide 0 . 100  to       .  000  per  cent 

Ferric  oxide 0 . 005  to       .  003  per  cent 

The  manufacture  of  zinc  oxide  from  the  metal  is  also  an 
important  industry  in  Silesia,  the  production  being  in  the 
neighborhood  of  about  one  thousand  metric  tons.  As  the 
Silesian  zinc  always  contains  lead  which  converted  into 
oxide  gives  a  yellowish  color  to  the  zinc  oxide,  carbon 
dioxide  from  burning  coke  is  introduced  into  the  distilling 
retort  which  converts  the  lead  into  carbonate,  according  to 
Ingalls.  The  zinc  oxide  is  collected  in  large  upright  bags 
similar  to  the  American  practice.  The  largest  works  in 
Silesia  is  the  Antionenhiitte. 

203.  The  cost  of  production  of  zinc  oxide  from  the  metal 
is  considerably  higher  than  that  of  zinc  oxide  produced 
direct  from  the  ore,  as  is  the  common  practice  in  this  coun- 
try, but  it  insures  the  absence  of  certain  objectionable 
impurities  like  cadmium,  which  is  considerably  more  vola- 


MANUFACTURE  OF  ZINC  OXIDE.  155 

tile  than  zinc,  and  produces  a  brown  oxide  which  would 
cause  a  discoloration  of  the  finished  product  if  it  were  not 
removed  in  the  process  of  the  manufacture  of  the  metal. 
As  the  majority  of  European  ores  contain  cadmium,  a  direct 
process  similar  to  that  used  in  this  country  is  out  of  the 
question. 

204.  Processes  in  Use  in  the  United  States.     In  the  United 
States  the  larger  part  of  the  zinc  oxide  produced  is  derived 
from  the  ore.     The  Florence,  Pennsylvania,  plant  of  the 
New  Jersey  Zinc  Company,  however,  manufactures  zinc 
oxide  from  the  metal  by  what'  is  substantially  the  French 
process,  the  metallic  zinc  being  heated  in  retorts,  volatilized, 
and  the  vapors  burned  to  the  oxide  which  is  drawn  into 
collecting  chambers  by  the  draught  from  a  high  chimney. 
The  material  so  collected  is  treated  to  further  purify  it  and 
improve  its  color.     The  greatest  care  must  be  exercised  in 
the  selection  of  the  metal  used  and  in  all  of  the  subsequent 
steps  of  the  process,  but  when  properly  operated  this  pro- 
cess   produces   the   purest    white    pigment    known.     The 
product    is    graded    in    a   manner   similar   to    the    Vielle 
Montagne,   and   is   known   under  the   name   of   Florence 
Green  Seal  and  Florence  Red  Seal. 

205.  The  Work  of  Jones  and  Wetherill.     The  invention 
of  the  American  process  for  the  manufacture  of  zinc  oxide 
is  ascribed  to  Samuel  T.  Jones,  who  constructed  a  furnace 
for  this   purpose  in   1850.     The   process   was   materially 
improved  and  placed  on  a  commercial  scale  by  Col.  Samuel 
Wetherill  in  1855,  who  worked  with  the  Franklinite  ores  of 
New  Jersey.     The  growth  of  the  industry  was  somewhat 
slow  at  first,  but  after  1880  it  developed  rapidly  and  con- 
stitutes to-day  one  of  the  largest  of  the  metallurgical  indus- 
tries.    Unlike  the  manufacture  of  the  white  lead  pigments, 
the   zinc   oxide   industry   has   shown   comparatively   few 
improvements  in  the  process  of  manufacture  during  the  last 


156  THE  LEAD   AND   ZINC  PIGMENTS. 

thirty  years.  While  the  principles  of  the  process  have 
remained  unchanged,  there  has  been  a  marked  improve- 
ment in  the  character  of  the  ore  sent  to  the  oxide  furnaces, 
which  is  now  first  given  a  roasting  to  drive  off  the  large 
amount  of  the  sulphur,  because  when  the  oxidation  of  the 
sulphides  and  the  volatilization  of  the  zinc  is  accomplished 
in  one  process  in  the  same  furnace,  the  collected  oxide  is 
contaminated  with  appreciable  amounts  of  zinc  sulphates 
and  a  considerable  amount  of  sulphur  dioxide  remains 
occluded  in  the  oxide  particles,  which  is  a  serious  considera- 
tion from  the  paint  manufacturer's  point  of  view. 

206.  Zinc  Oxide  Plants  in  the  United  States.     At  the 
present  time  there  are  four  plants  engaged  in  the  manufac- 
ture of  commercially  pure  zinc  oxide,  and  they  are  located 
in   the  States   of  New  Jersey  and   Pennsylvania.     These 
plants  are  operated  by  the  New  Jersey  Zinc  Company. 
Another  plant  is  located  at  Mineral  Point,  Wisconsin,  and 
operated  by  the  Mineral  Point  Zinc  Company,  which  is 
affiliated  with  the  New  Jersey  Zinc  Company.     The  zinc 
oxide  produced  at  this  plant,  however,  contains  varying 
quantities   of  lead  sulphate,   and  is   graded   accordingly. 
Other  zinc  oxide  plants  are  located  near  Joplin,  Missouri; 
Coffeyville,  Kansas;  and  at  Canon  City,  Colorado;  but  as 
the  pigments  produced  at  these  plants  contain  a  large  per- 
centage of  lead  sulphate,  the  procedure  in  these  plants  will 
be  considered  separately. 

207.  Development  of  the  New  Jersey  Zinc  Mines.     The 
development  of  the  New  Jersey  zinc  mines  constitutes  a 
very  interesting  chapter  in  the  development  of  our  mineral 
resources.    The  mines  at  Sterling  and  Franklin  were  discov- 
ered in  the  latter  part  of  the  eighteenth  century,  it  is  said, 
by  a  party  of  Swedish  miners  who  were  traveling  overland 
from  Baltimore  to  New  York.     Some  ore  is  supposed  to 
have  been  sent  to  England  about  this  time,  but  we  find  no 


MANUFACTURE  OF  ZINC   OXIDE 


157 


S    u 

35 

«  «J 
^  P^ 

N    W 


158  THE  LEAD   AND   ZINC  PIGMENTS. 

record  of  its  having  been  received  or  treated.  In  any  case, 
the  mines  were  known  to  exist  as  early  as  1824,  when 
Messrs.  Van  Uxen  and  Keating  described  some  of  the 
minerals.  The  first  mining  done  at  Franklin  was  when  the 
United  States  Government  made  the  standard  weights  and 
measures.  They  imported  some  workmen  from  Belgium, 
built  a  spelter  furnace  at  Washington,  and  made  the  zinc 
partly  of  ore  from  Franklin  and  from  scattered  boulders  of 
ore  found  in  Sparta  Valley,  and  partly  from  ore  from 
Perkiomen,  Pennsylvania.  The  old  pit  from  which  this 
ore  was  taken  was  known  as  the  "  Weights  and  Measures 
Opening,"  and  was  in  existence  until  about  1900,  whe,n  the 
mining  operations  caused  its  disappearance.  No  further 
mining  was  done  until  1848,  when  the  mines  at  Sterling 
Hill  were  opened.  Mining  did  not  begin  at  Franklin  until 
a  couple  of  years  later. 

208.  At  first  an  attempt  was  made  to  manufacture 
spelter  from  the  ore,  but  this  was  not  successful,  and  the 
manufacture  of  oxide  of  zinc  was  started  at  Newark.    At 
first  the  ore  was  worked  in  reverberatory  furnaces,  and  the 
product  was  of  a  rather  poor  quality,  and  the  cost  extremely 
high.     Later  the  ore  was  treated  in  muffles  by  a  process 
said  to  have  been  discovered  by  Mr.  Farrington,  the  Super- 
intendent of  the  works,  but  which  was  identical  with  one 
patented  by  Atkinson  in  England,  April  2,   1796.     Still 
later  the  present  method  of  manufacturing  oxide  of  zinc 
direct  from  ore  was  discovered  and  patented  by  Col.  Samuel 
Wetherill. 

209.  Controversy    regarding     the     Ownership     of     the 
Deposits.     At  the  time  that  mining  operations  were  first 
started  in  Franklin,  the  mineral  rights  had  been  sold  to  two 
different  companies  by  Col.  Samuel  Fowler,  who  owned  the 
Mine-Hill  farm,  on  which  the  principal  deposit  is  located. 
In  the  first  deed  he  conveyed  all  the  gold,  silver,  copper, 


MANUFACTURE  OF  ZINC  OXIDE.  159 

lead,  zinc  and  other  ores  and  minerals  containing  gold, 
silver,  copper,  lead  and  zinc,  except  the  metal,  mineral,  or 
ore  known  as  Franklinite  when  it  exists  separate  and  apart 
from  the  zinc,  and  in  the  second  deed  he  conveyed  all  the 
mineral  rights  that  had  been  reserved  in  the  first  deed. 
The  ambiguous  nature  of  these  conveyances  led  to  litiga- 
tion, which  lasted  almost  continuously  from  1854  to  1897, 
and  was  only  concluded  when  the  present  New  Jersey  Zinc 
Company  acquired  the  title  to  all  mineral  rights  in  the 
Mill-Hill  farm.  The  reason  that  the  deeds  were  made  in 
this  way  was  that  at  that  time  it  was  believed  that  there 
were  two  separate  veins,  one  consisting  almost  entirely  of 
Franklinite,  and  the  other  of  other  zinc  minerals.  Sub- 
sequent work  has  proved  that  this  was  not  the  case,  and 
the  point  to  be  decided  by  litigation  was  whether  the  vein, 
which  is  a  mixture  essentially  of  the  minerals  Franklinite, 
willemite,  zincite  and  calcite,  was  "  Franklinite  separate 
and  apart  from  the  zinc,"  or  "  zinc." 

210.  Composition  of  Franklinite  Ore.  The  Franklin  ore  l 
of  New  Jersey,  from  which  the  larger  portion  of  our  zinc 
oxide  is  produced,  is  a  complex  ore  composed  of  Franklinite, 
willemite,  and  calcite  in  varying  proportions,  together  with 
occasional  quantities  of  zincite,  tephroite,  garnet,  fowlerite, 
and  a  few  other  minerals.  As  it  comes  from  the  mines  the 
ore  varies  widely  in  composition,  but  the  following  will  serve 
as  an  example: 

Per  cent. 

Iron  sesquioxide 32 .06 

Manganese  protoxide 1 1 . 06 

Zinc  oxide 29.35 

Calcium  carbonate 12 . 67 

Silica  and  insoluble  matter .  .  14 . 86 


100.00 
Mineral  Industry,  1893,  page  673. 


160  THE   LEAD   AND   ZINC  PIGMENTS. 

211.  These  figures  may  be  calculated  to  the  following 
mineral  composition: 

Per  <ent. 

Franklinite 51 .92 

Willemite 31 . 58 

Calcite 12.67 

Zincite 0.52 

Tephroite  and  other  silicates 3.31 


100.00 

212.  The  specific  gravity  of  these  minerals  is  as  follows: 

Name.  Specific  Gravity. 

Zincite 5.43-5.70 

Franklinite 5.00-5.09 

Tephroite 4.00-4.12 

Willemite 3.89-4.18 

Calcite 2.50-2.77 

213.  Chemical  Composition.   The  chemical  composition 
of  these  minerals  is  about  as  follows : 

Zincite,  sometimes  spoken  of  as  "  red  zinc  ore,"  is  when 
pure,  oxide  of  zinc,  containing  80.3  per  cent  metallic  zinc. 
It  is  frequently  contaminated  with  manganese. 

Franklinite  is  a  complex  mineral  found  in  almost  inex- 
haustible quantities  in  New  Jersey.  It  contains  about 
66  per  cent  oxide  of  iron,  12  per  cent  oxide  of  manganese 
and  22  per  cent  oxide  of  zinc. 

Willemite  is  zinc  silicate  containing  about  73  per  cent 
zinc  oxide  and  27  per  cent  silica. 

214.  Preliminary  Treatment  of  the  Ore.   The  ores  are 
usually   crushed   and   concentrated   at  the  mines   before 
shipment.     The   concentrates,   which  consist   of  the  zinc 
minerals  in  a  fairly  fine  state  of  division,  are  treated  at  the 
oxide  works  about  as  follows :  The  ore  is  mixed  with  about 


MANUFACTURE  OF  ZINC  OXIDE. 


101 


162  THE   LEAD   AND    ZINC  PIGMENTS. 

one-fifth  its  weight  of  high  grade  anthracite  coal,  and 
charged  into  fire-brick  lined  revolving  furnaces  heated  by 
producer  gas,  the  ore  being  heated  to  bright  redness. 
The  ore,  after  passing  through  the  furnace,  is  discharged 
into  a  cooler,  from  which  it  goes  to  the  storage  bins. 

215.  When  the  ore  is  required  for  use,  it  is  passed  over 
magnetic    separators    and    jigs   into    five    products.     The 
first  of  these  consists  of  the  magnetic  minerals,  mainly 
Franklinite.     This  is  all  used  for  making  oxide  of  zinc  and 
gives  the  best  quality  produced.     The  second  product  is 
called   half-and-half    and    consists    of    the   less    magnetic 
minerals  of  the  ore.     This  is  also  used  for  making  oxide 
of  zinc,  but  not  being  as  pure  as  the  Franklinite  gives  a 
smaller  proportion  of  the  higher  grades.     The  third  product 
is  willemite  from  the  jigs,  which  is  used  for  making  spelter 
or  metallic  zinc.     The  fourth  product  is  the  tailings  from 
the  jigs,  which  is  thrown  away.     The  fifth  product  is  the 
fine  dust  from  the  ore,  which  is  removed  before  separat- 
ing.   This  is  also  used  in  the  manufacture  of  oxide  of 
zinc. 

216.  The   Oxide   Furnaces.  The   furnace  used   for  this 
purpose  is  Q  shaped  in  section,  with  a  flat   iron   grate 
about  four  feet  wide  and  ten  feet  long  above  a  closed  ash 
pit.    The  grate  is  composed  of  heavy  iron  plates  about 
six  inches  wide,  lying   close   together,  each   plate   being 
perforated  with  a  large  number  of  small  holes  through  which 
air  is  blown  at  a  pressure  of  two  to  four  inches  water- 
gauge.     The  roof  of  the  arch  over  the  grate  is  of  fire-brick. 
The  doors  at  each  end  of  the  furnace  are  always  kept 
closed,  except  when  charging.    A  series  of  .these  furnaces 
are  built  in  a  row  and  the  products  of  combustion  from  each 
furnace  containing  the  zinc  oxide  fume  pass  into  common 
pipe  lines  to  the  collecting  system.     In  operation  a  thin 
layer  of  anthracite  coal,  nut  size,  is  placed  on  the  grate, 


MANUFACTURE  OF  ZINC  OXIDE. 


163 


164  THE   LEAD   AND   ZINC   PIGMENTS. 

and  assisted  by  a  light  blast  is  allowed  to  burn  until  ignited. 
When  burning  in  all  parts,  ore  mixed  with  about  half  its 
weight  of  finely  powdered  anthracite  coal  and  sometimes 
limestone,  according  to  the  composition  of  the  ore,  is 
spread  in  a  layer  five  to  seven  inches  thick  over  the  ignited 
fuel  and  the  doors  at  each  end  of  the  furnace  closed,  the 
blast  being  slowly  admitted  under  the  grate  and  increased 
to ;* the  maximum  as  required.  During  the  charging,  a 
damper  in  the  pipe  over  the  furnace  is  closed  so  that  the 
gases  produced  cannot  go  to  the  bag-room.  The  zinc  is 
reduced  to  the  metallic  condition,  volatilized  and,  immedi- 
ately catching  fire,  is  burned  to  a  dazzling  white  fume, 
which  is  drawn  away  by  the  suction  fans. 

217.  At  the  end  of  about  six  hours  the  operation  is 
complete,  upwards  of  90  per  cent  of  the  zinc  in  the  ore 
having  been  driven  off  as  the  oxide,  the  remainder  together 
with  the  iron  and  manganese  being  left  in  the  residue  on 
the  grate.     One  man  usually  attends  to  a  block  of  six 
double  furnaces,   charging  them  one  after  the  other  at 
intervals  of  one  hour,  which  insures  the  necessary  uni- 
fornlity   in   the   process.     The   ashes   are   removed   from 
below  the  grate  once  in  twenty-four  hours.     The  charge 
of  prepared  ore  for  a  double  furnace  is  about  five  hundred 
pounds. 

218.  Collection  of  the  Fume.   The  white  fume  escaping 
through  the  flue  in  the  top  of  each  furnace  passes  into  a 
large   common   pipe   line   extending   above   the   furnaces 
which  leads  to  two  brick  towers  where  the  heavier  and  less 
pure  particles  of  oxide  settle  out.     The  somewhat  purified 
fume  is  then  blown  by  means  of  fans  to  a  large  cooling 
room  where  a  further  settling  takes  place.    The  fume, 
which  is  now  quite  cool,  passes  on  to  the  bag-rooms,  where 
the  main  pipes  or  flues  are  joined  to  several  distributing 
sheet-iron  pipes  in  the  top  of  the  bag-rooms.     From  each 


MANUFACTURE  OF  ZINC  OXIDE.  165 


FIG.  59.  —  BLOWER  ROOM.  —  PALMERTON  WORKS. 


166  THE   LEAD   AND   ZINC   PIGMENTS. 

pipe  hang  muslin  bags  6  feet  in  diameter  and  about  forty 
feet  in  length.  The  products  of  the  combustion  of  the 
fuel  contained  in  the  fume  pass  through  the  bags,  while 
the  condensed  oxide  of  zinc  collects  inside  and  is  shaken 
down  at  regular  intervals,  a  somewhat  disagreeable  task, 
as  the  atmosphere  in  the  bag-room  is  strong  with  the 
escaping  sulphurous  acid  gas.  The  zinc  oxide  after  removal 
from  the  bags  is  graded  according  to  color  and  purity  and 
then  bolted  through  silk  cloth  in  machines  similar  to  those 
used  for  bolting  flour  and  packed  into  barrels  holding 
about  200  pounds,  in  which  form  it  is  put  on  the  market. 

219.  Palmerton  Plant.     The  Palmerton  plant  of  the  New 
Jersey  Zinc  Company  contains  24  blocks  of  oxide  furnaces, 
12  furnaces  to  the  block,  or  a  total  of  288  furnaces,  and  as 
about  200  square  feet  of  bag  surface  is  required  for  1  square 
foot  of  grate  surface,  this  means  about  850,000  square  feet 
of  bag  surface,  equal  to  27  miles  of  bags,  which  are  contained 
in  four  bag-rooms,  having  a  combined  floor  area  of  nearly 
two  acres.     Eight  exhaust  fans,  each  driven  by  its  own 
motor,  are  required  for  conveying  the  fume  from  the  fur- 
naces to  the  bag-houses.    The  bag-houses  and  packing 
house  form  a  rectangle.    The  packing  house  is  four  stories 
in  height,  and   the  first  and  fourth  floors  contain  enor- 
mous bins  for  the  storage  of  unpacked  oxide.     By  means  of 
an  electric  elevator  the  oxide  is  sent  to  the  bolting  machines 
on  the  third  floor,  and  then  to  the  barrel  packing  machines 
on  the  second  floor.     The  barreled  oxide  is  then  conveyed 
to   the  warehouses,  which  have  a  capacity  of   9,000,000 
pounds  of  oxide. 

220.  Purity  of  New  Jersey  Zinc  Oxide.     The  Wetherill 
process,  while  simple  in  principle,  is  subject  to  the  same 
difficulties  that  always  attend  a  sublimation  or  volatiliza- 
tion process,  as  all  of  the  volatile  constituents  of  the  ore  as 
well  as  some  of  the  constituents  of  the  clinker  ash  pass  over 


MANUFACTURE  OF  ZINC  OXIDE. 


167 


168  THE   LEAD   AND   ZINC  PIGMENTS. 

and  are  collected  with  the  oxide.  This  will  include  arsenic, 
antimony,  cadmium,  sulphur  dioxide,  lead,  iron,  manga- 
nese, silica,  lime,  and  magnesia.  The  art  of  the  manufac- 
turer consists  in  keeping  these  impurities  down  to  a  negli- 
gible quantity.  Under  average  conditions  the  purity  of 
New  Jersey  zinc  oxide  is  about  as  follows : 

Name.  Purity. 

"  Special  "    99. 121  per  cent. 

"  xx  Red  " 98.796  per  cent. 

"  Selected  " 99.227  per  cent. 

"  xx  " 99.051  per  cent. 

221.  Zinc   oxide   produced   from   the   metal   itself   as 
exemplified    by   the    Florence   Green   Seal   and   Florence 
Red   Seal   brands   contains   99.448  per   cent   and  99.336 
per   cent,    respectively,   of    zinc    oxide,   which   indicates 
that  the  production  of  oxide   from  the  ore  has  reached 
an  extremely  high  state  of  development  and  metallurgical 
perfection. 

222.  Furnace  Assays.     Variations  in  the  character  of  the 
ore  necessitate  different   conditions  of   heat,  air  and  fuel 
supply,  and  a  certain  relation  between  the  volume  of  the 
gas,  the  amount  of  zinc  oxide  that  it  carries  and  the  dimen- 
sions of  the  flues  and  mains  must  be  adhered  to.     According 
to  Ingalls  (Metallurgy  of  Zinc  and  Cadmium),  the  average 
furnace  charge  consists  "  of  100  parts  of  Franklinite,  55.68 
parts  of  reducing  coal  and  49.95  parts  of  heating  coal.     The 
ore  assaying  about  34  per  cent  of  zinc  oxide  yielded  24.50 
per  cent  of  first  quality  zinc  oxide  assaying  99.87  per  cent 
zinc  oxide,  and  1.5  per  cent  of  second  quality  assaying  99.34 
per  cent.     The  residuum  amounted  to  66.22  per  cent  of  the 
ore.     Its  composition,  according  to  C.  F.  McKenna,  was 
about  36.43  per  cent  ferric  oxide,  15.83  per  cent  manganese 
oxide,  and  9.85  per  cent  zinc  oxide,  but  the  percentage  of 


MANUFACTURE  OF  ZINC  OXIDE. 


169 


FIG.  61.  —  A  BAG-ROOM.  —  PALMERTON  WORKS. 


170 


THE  LEAD   AND   ZINC  PIGMENTS. 


MANUFACTURE   OF   ZINC   OXIDE.  171 

zinc  oxide  was  sometimes  as  high  as  11.85  per  cent.  Besides 
the  iron,  manganese  and  zinc  oxides  the  residuum  contains 
lime,  magnesia,  and  alumina." 

223.  The  ores  at  Franklin  have  proved  to  be  particu- 
larly well  adapted  for  producing  oxide  as  they  are  practically 
free  from  the  impurities  which  are  most  objectionable  in 
the  pigment,  that  is,  lead,  cadmium  and  sulphur. 

However,  since  the  introduction  of  magnetic  separation 
the  Franklinite  ore  used  has  averaged  only  about  28  per 
cent  zinc  oxide,  of  which  about  83  per  cent  is  volatilized  and 
collected  as  zinc  oxide. 

224.  Spiegeleisen.     The  residuum  remaining  in  the  oxide 
furnace  is  smelted  in  blast  furnaces  for  spiegeleisen.     In 
this  process  the  zinc  is  reduced,  volatilized  and  partially 
oxidized,  and  when  obtained  in  the  condensing  system  a 
portion  of  it  is  collected  as  a  blue  powder  containing  about 
90  per  cent  zinc,  and  the  remainder  as  a  yellowish  brown 
dust  containing  about  75  per  cent  of  zinc  oxide,  and  is 
sent  to  the  spelter  furnaces  for  reduction. 

225.  Mineral  Point  Works.     At  the  Mineral  Point  works 
the  zinc  oxide  is  made  by  a  process  very  similar  to  the  above, 
the  only  difference  being  that  there  is  a  much  more  elabo- 
rate system  of  flues  and  dust-chambers  between  the  fur- 
naces and  bag-rooms.     The  sulphur  dioxide  liberated  from 
the  ore  is  used  for  the  manufacture  of  sulphuric  acid.    Very 
few  of  the  Western  ores  are  well  adapted  for  the  manufac- 
ture of  oxide  as  they  are  generally  less  pure  than  the  ore 
from  Franklin,   containing,   especially,  lead,  so  that  the 
Western  oxide  always  contains  sulphate  of  lead.    This  varies 
in  the  different  grades  from  a  fraction  of  one  per  cent  to 
nearly  25  per  cent.     Sulphate  of  lead  is  quite  different  from 
white  lead,  being  a  much  more  inert  material,  which  is  not 
so  poisonous   and   not  so  likely  to  be  discolored  by  the 
action  of  sulphur  gases.     In  the  West  the  same  amount  of 


172 


THE   LEAD   AND   ZINC  PIGMENTS. 


MANUFACTURE   OF   ZINC  OXIDE. 


173 


174  THE   LEAD   AND   ZINC   PIGMENTS. 

care  must  be  exercised  as  in  the  East,  and  in  addition  great 
skill  is  needed  in  mixing  the  various  ores  in  proper  propor- 
tions, so  as  to  obtain  a  good  quality  of  product.  The  grad- 
ing in  the  East  is  almost  entirely  by  color,  but  in  the  West, 
it  is  by  both  color  and  lead  content. 


CHAPTER  XV. 

PROPERTIES  AND  USES  OF   ZINC  OXIDE. 

226.  Properties.     Zinc  oxide  is  perhaps  the  whitest  of  the 
valuable  pigments  at  the  disposal  of  the  painter  and  paint 
manufacturer.     It  has  a  specific  gravity  of  about  5.60  as 
compared  with  6.45  for  white  lead,  and  is  a  much  more 
voluminous  or  bulky  pigment,  a  gallon  measure  containing 
only  three  to  five  pounds  of  loosely  filled  oxide.     When  hot 
it  possesses  a  lemon  yellow  color,  but  on  cooling  regains  its 
original  whiteness.     Heated  by  means  of  an  oxyhydrogen 
flame,  it  emits  a  brilliant  white  light  and  after  cooling, 
exhibits  a  marked  phosphorescence  in  the  dark,  for  a  con- 
siderable length  of  time.     In  the  electric  furnace  it  rapidly 
volatilizes  and  condenses  in  long  transparent  crystals. 

227.  Solubility.     Zinc  oxide  is  readily  soluble  in  all  of 
the  common  acids,  such  as  hydrochloric,  sulphuric,  nitric, 
and  acetic  acids,  affording  colorless  solutions,  and  is  not 
readily  precipitated  from  them  by  alkalies,  as  zincates  are 
formed  which  are  quite  soluble.     One  of  the  simplest  tests 
for  the  presence  of  zinc  in  a  pigment  or  paint  is  to  dissolve 
a  portion  of  the  sample  in  hydrochloric  acid,  precipitate  any 
iron  and  aluminum  that  may  be  present  with  ammonia, 
filter,  make  slightly  acid  with  hydrochloric  acid,  and  then 
add  a  few  drops  of  potassium  ferrocyanide.    A  gelatinous 
whitish  precipitate  indicates  the  presence  of  zinc. 

228.  Composition   of   Commercial   Grades.     Zinc   oxide 
varies  in  purity  according  to  the  ore  from  which  it  is  pro- 
duced, and  the  method  of  furnacing.     The  following  analy- 
ses drawn  from  various  reliable  sources  will  give  some  idea 
commercial  grades  to  be  found  on  the  market. 

175 


176 


THE   LEAD   AND   ZINC  PIGMENTS. 


229.    Analyses  of  Oxide  of  Zinc  made  from  the  Ore. 


Eastern. 

Special. 

XX  Red. 

Selected. 

XX. 

Insoluble  

Per  cent. 
.045 
.302 
.019 
.215 

.027 
.066 

Per  cent. 
.047 
.530 
.089 
.261 

.057 
.078 

Per  cent. 
.025 
.230 
.019 
.183 

.067 
.065 

Per  .cent. 
.024 
.246 
.007 
.249 

.046 
.074 

Water  (H2O)  
Carbonic  acid  (CO2) 

Sulphuric  acid  (SO3)  
(Total  sulphur  as) 
Sulphurous  acid  (SO2)  
(Red.  Power  equiv.  to) 
Chlorine  (Cl)  
Carbon  (C)     

Oxide  of  lead  (PbO)  
Oxide  of  cadmium  

.042 
Trace 
None 
None 

.031 
Trace 
None 
None 

.118 
Trace 
None 
None 

.171 
Trace 
None 
None 

.092 
.017 

Oxide  of  bismuth  (Bi2O3)  .... 
Oxide  of  copper  (CuO) 

Oxide  of  tin  (SnO2) 

Oxide  of  silver  (Ag2O) 

Oxide  of  iron  (Fe2O,) 

.020 
.017 
.022 
.078 

.011 
.013 
.005 
.054 

.045 
.017 

Oxide  of  manganese  (MnO).  . 
Alumina  (A12O?)  
Lime  (CaO)...'.  
Magnesia  (MgO)  

Arsenious  acid  (As2O3)  

.026 
Trace 
99.121 

.028 
Trace 

98.796 

.011 
Trace 

99.227 

.023 
Trace 
99  051 

Oxide  of  antimony  (Sb2O3)..  . 

OxiHp  of  7ino 

230.   Analyses  of  Zinc  Oxide  made  from  Spelter. 


Florence  Green 
Seal. 

Florence  Red 
Seal. 

Insoluble       

Per  cent. 
0  030 

Per  cent. 
0  049 

Water  (H  O) 

0  010 

0  044 

Carbonic  acid  (CO2) 

None 

0  003 

Sulphuric  acid  (SO,)  (Total  sulphur  as).  . 
Sulphurous  acid  (SO2)(Red  Power  equiv.  to) 
Chlorine  (Cl)  
Carbon  (C)                         

0.157 
0.003 
0.031 

0.151 
0.005 
0.088 

Oxide  of  lead  (PbO)  
Oxide  of  cadmium  
Oxide  of  bismuth  (Bi2O^)  

0.299 
Trace 
None 

0.285 
Trace 
None 

Oxide  of  copper  (CuO) 

None 

None 

Oxide  of  tin  (SnO2) 

Oxide  of  silver  (Ag2O)                   

Oxide  of  iron  (Fe2O3)  
Oxide  of  manganese  (MnO)  
Alumina  (A12O3)          

0.022 
Trace 

0.039 
Trace 

Lime  (CaO) 

Magnesia  (MgO) 

Arsenious  acid  (As2Os) 

Trace 

Trace 

Oxide  of  anti'nonv  (Sb0O,)             .  . 

Trace 

Trace 

Oxide  of  zinc  (ZnO)  

99.448 

99.336 

PROPERTIES  AND  USES  OF   ZINC   OXIDE. 


177 


231.   Analyses  of  Mineral  Point  Zinc  Oxides. 


Prime. 

Standard. 

Sterling. 

Leaded. 

Insoluble  
Water  (H2O)  

0.04 
0.06 

Trace 
0.90 

0.09 
0.11 

Trace 
0.11 

Carbonic  acid  (CO.,)  
Sulphuric  acid   (SO3)    (Total 
sulphur  as) 

0.10 
1  25 

0.08 
1  63 

0.08 
3  42 

Trace 
5  62 

Sulphurous  Acid  (SO2)  (Red. 
Power  eouiv   to) 

0  033 

0  05 

0  03 

0  08 

Chlorine  (Cl) 

0  05 

N  D 

N  D 

N  D 

Carbon  (C)  
Oxide  of  lead  (PbO) 

None 
2  72 

N  D 
3  80 

N  D 
8  79 

N  D 
15.08 

Oxide  of  cadmium  (CclO)  .... 
Oxide  of  bismuth  (Bi,O.t)  
Oxide  of  copper  
Oxide  of  tin  (SnO,)  
Oxide  of  silver  (Ag2O)  
Oxide  of  iron  (Fe2O3) 
Alumina  (A12O3)  

0.06 
None 
None 
None 
Nome 

0  08 

0.14 
N  D 
N  D 
NI) 
ND 

0  05 

0.25 
N  D 
N  D 
N  D 
ND 

0  06 

0.17 
N  D 
N  D 
N  D 
ND 

0.05 

Lime  (CaO)  
Magnesia  (MgO)  

None 
None 

Trace 
Trace 

N  D 
N  D 

ND 

N  D 

Arsenious  acid  (As2().,)  
Oxide  of  antimony  fSbjOg).  .  . 
Oxide  of  zinc  (by  difference)  . 
Equivalent  to 
PbSO4 

0.12 
None 
95.52 

3  70 

N  D 
ND 
93.40 

5  17 

N  D 
ND 
87.39 

11  95 

ND 
ND 

78.97 

20  50 

ZnSO4  

0.42 

0.40 

0.45 

0.24 

PbSO   range 

0  to  5  00 

0  to  5.00 

5  00  to 

16  00  to 

16.00 

25.00 

232.   Analyses  of  Zinc  Oxide.1       Scott. 


I 

II 

III 

IV 

V 

Zinc  oxide 

99  80 

96  81 

89  31 

77  35 

48  40 

Zinc  sulphate 

0  00 

0  15 

0  96 

0  13 

0  67 

Lead  sulphate 

0  00 

2  75 

9  33 

21  01 

50  40 

Lead  oxide 

0  00 

0  00 

0  27 

1  38 

0  32 

Insoluble  matter.   .    . 

Trace 

0  22 

0  03 

0  08 

0  10 

Moisture  

0  20 

0  07 

0  10 

0  05 

0.11 

Specific  gravity  

5  560 

5  795 

5  620 

5.800 

5.770 

I.    Pure  zinc  oxide  made  from  spelter. 
II.    Zinc  oxide  made  from  silicate  ore. 

III.  Zinc  oxide  made  from  blende. 

IV.  Leaded  zinc  oxide  made  from  mixed  ore. 
V.    Zinc-lead  made  from  zinc  and  lead  ores. 

1  Scott,  Oxide  of  Zinc,  page  15. 


178 


THE   LEAD   AND    ZINC   PIGMENTS. 


233.   Hooker  in  his  pamphlet  on  "  Zinc  White  "  records 
the  following  analyses : 


I 

II 

III 

IV 

V 

Zinc  oxide  
Sulphur  dioxide  

98.80 
0.007 
0.35 
0.35 
0.24 

98.40 
0.04 
0.89 
0.00 
0.30 

93.60 
0.08 
1.29 
4.60 
0.20 

92.90 
0.43 
4.35 
1.60 
0.31 

84.60 
0.06 
1.16 
13.63 
0.21 

Zinc  sulphate  

Lead  sulphate 

Moisture 

99.747 

99.63 

99.77 

99.59 

99.65 

234.  Sulphur  Dioxide  and  Zinc  Sulphate.    Variation  in 
the  lead  content  of   a  commercial  zinc  oxide  is  of   small 
moment,   as  compared   with  the  percentages  of  sulphur 
dioxide  and  zinc  sulphate,  and  as  Hooker  states,  if  these 
impurities    are    not    largely  eliminated,    "  the    grinder's 
troubles  are  many  and  livering  and  granulation  of  the  paint 
can  be  looked  for." 

235.  Imported  Zinc  Oxides.   The  imported  zinc  oxides 
are  prepared,  as  has  been  explained,  from  the  burning  of 
the  metal  or  spelter;  they  possess  exceeding  whiteness  and 
when  used  with  tinting  colors  exhibit  a  purity  of  tone  far 
surpassing  white  lead,  as  can  be  easily  demonstrated  by 
preparing  two  light  blues  of  as  nearly  the  same  tint  as 
possible,  using  in  the  one  case  Prussian  blue  and  zinc  oxide 
and  in  the  other  case  white  lead  and  Prussian  blue;  it  will 
be  found  that  the  blue  prepared  with  the  zinc   oxide  is 
of  a  very  much  cleaner  tint.     Using  equal  quantities  of 
Prussian  blue  it  will  be  noticed  that  only  about  one-half 
as  much  zinc  oxide  is  required  to  produce  substantially  the 
same  tint  as  with  white  lead  (Old  Dutch  process).     Stated 
in  more  accurate  terms  the  tinting  strength  of  zinc  and  lead, 
weight  by  weight,  is  as  11  is  to  20. 


PROPERTIES  AND  USES  OF   ZINC   OXIDE.  179 

236.  Comparative  Prices.   The  domestic  Florence  Green 
Seal  and  Red  Seal  oxides  prepared  from  the  metal  are  sub- 
stantially equal  to  the  imported  oxides,  and  in  the  opinion 
of  the  writer  may  be  substituted  with  advantage  in  almost 
every  instance    for   them.     The    following   figures    (1908) 
show  the  comparative  prices  of  the  various  zinc  oxides : 

Paris  Green  Seal 10J  cents  f.o.b.  New  York. 

Paris  Red  Seal 8|  cents  f.o.b.  New  York. 

Antwerp  Green  Seal  .  .  10J  cents  f.o.b.  New  York. 

Antwerp  Red  Seal  ...  8i  cents  f.o.b.  New  York. 

Florence  Green  Seal.  .  7    cents  f.o.b.  Philadelphia. 

Florence  Red  Seal  ...  6J  cents  f.o.b.  Philadelphia. 

New  Jersey  XX 5   cents  f.o.b.  Detroit. 

Zinc  Lead  White 4J  cents  f.o.b.  Detroit. 

237.  Lack  of  Affinity  for  Moisture.   One  of  the  greatest 
faults  to  be  found  with  the  zinc  oxide  pigments  is  their 
lack  of  affinity  for  damp  surface,  i.e.,  paints  high  in  zinc 
oxide  lack  penetration  when  applied  over  a  damp  surface, 
tne  resulting  manifestations  being  peeling  and  cracking. 
It  is  the  custom  with  many  painters  to  cover  kegs  of 
strictly  pure  white  lead  with  a  little  water  to  prevent  the 
formation  of  "  skins."     In  the  case  of  combination  white 
leads  containing  zinc  oxide,  such  treatment  is  detrimental, 
as  it  usually  results  in  the  hardening  of  the  lead  and  the 
formation  of  "  crusts." 

238.  Zinc  Oxide  as  a  Paint  Pigment.   Much  has  been 
written  about  the  properties  of  zinc  oxide  and  its  value 
as    a   paint   pigment.     Judging   from    the   experience   of 
American  paint  manufacturers  it  has  not  proved  satis- 
factory when  used  alone  as  a  pigment  for  outside  house 
paints  owing  to  its  excessive  oil-taking  capacity,  producing 
a  very  thin  coat  and  the  production  of  a  hard  brittle  paint 
film.    As  a  base  for  enamels,  however,  it  leaves  but  little 


180  THE   LEAD   AND   ZINC  PIGMENTS. 

to  be  desired  as  regards  whiteness,  body  and  wearing 
value.  By  far  the  larger  amount  of  zinc  oxide  produced 
is  used  in  the  manufacture  of  mixed  paints  and  combi- 
nation white  leads.  When  used  with  lead  pigments  maxi- 
mum wearing  value  is  undoubtedly  secured,  although  paint 
manufacturers  are  not  agreed  as  to  the  most  desirable 
proportions.  Climate  and  locality  have  much  to  do  with 
this  lack  of  agreement. 

239.  Along  the  sea  coast  a  paint  high  in  lead  and  low 
in   zinc   has   not  proved  satisfactory,   and   the  writer  is 
informed  that  the  best  lighthouse  specifications  call  for 
75  per  cent  zinc  and  25  per  cent  lead.     Inland,  the  same 
conditions  do  not  hold,  and  in  the  majority  of  high  class 
paints  the  zinc  and  lead  pigments  are  present  in  not  far 
from   equal   quantities,   disregarding  any  inert   pigments 
that  may  be  present.     Sixty-one  analyses,  made  by  the 
writer,  of  the  leading  brands  of  mixed  paints  sold  in  this 
country,  showed  an  average  ratio  of  lead  pigments  to  zinc 
oxide  of  45 : 55.      Paints  prepared  expressly  for  inside  use 
are  usually  high  in  zinc  and  low  in  lead,  the  ratio  being 
usually  75-80  parts  zinc  to  25-20  parts  lead.     This  is  due 
primarily  to  the  fact  that  zinc  oxide  is  not  affected  by 
sulphur  gases  in  the  same  way  as  white  lead,  as  zinc  sulphide 
is  white  whereas  lead  sulphide  is  black,   and  therefore, 
a  paint  containing  a  large  quantity  of  white  lead  used  on 
interior  work  will  soon  darken,  especially  where  gas  or 
coal  is  burned.     The  inertness  of  zinc  oxide  toward  the 
various  tinting  colors  also  renders  it  especially  valuable  in 
the  manufacture  of  tinted  mixed  paints,  notably  the  blues, 
yellows  and  greens. 

240.  The  foregoing  statements  will  give  some  idea  of 
the  uses  and  extent  to  which  zinc  oxide  has  been  put  in 
the  paint  industry  as  compared  with  white  lead.    A  glance 
at  the  following  table  of  production  shows  that  the  use  of 


PROPERTIES  AND  USES  OF  ZINC   OXIDE. 


181 


zinc  oxide  as  a  pigment  is  rapidly  on  the  increase.  This 
is  true  not  only  in  the  regular  lines  of  house  paints  but 
in  the  special  lines  as  well,  such  as  dipping  paints  and 
enamels,  as  a  base  for  striking  organic  colors  upon,  etc. 
When  it  is  considered  that  zinc  oxide  is  a  very  young  pig- 
ment as  compared  with  white  lead,  it  having  been  in  use 
for  only  a  comparatively  short  period  of  years,  it  is  evi- 
dent from  the  ready  favor  with  which  it  has  been  received 
by  paint  manufacturers  as  indicated  by  its  present  enor- 
mous consumption  that  it  at  least  merits  equal  importance 
and  consideration  with  white  lead. 

241.   Production  and  Value  of  Zinc  Oxide,  1880-1907. 


Year. 

Quantity. 

Value. 

Year. 

Quantity. 

Value. 

1880 

20,214,000 

$"63,738 

1894 

39,974,000 

$1,399,090 

1881 

20,000,000 

700.000 

1895 

41,420,000 

1,449,700 

1882 

20,000,000 

700,000 

1896 

40,000,000 

1.400,000 

1883 

24,000,000 

840,000 

1897 

50,000,000 

1,750,000 

1884 

26,000,000 

910,000 

1898 

66,000,000 

2,310,000 

J885 

30,000,000 

,050,000 

1899 

80,292,000 

3,211.680 

1886 

36,000,000 

,440,000 

1900 

97,680,000 

3,667,210 

1887 

36,000.000 

,440,000 

1901 

93,000,000 

3,720,000 

1888 

40,000,000 

,357,600 

1902 

105,460,000 

4,023,299 

1889 

33,940,000 

,357,600 

1903 

125,924,000 

4,801,718 

1890 

,600,000 

1904 

126,626,000 

4,808,482 

1891 

47,400,000 

,600,000 

1905 

136,206,000 

5,520,240 

1892 

55,000,000 

2,200,000 

1906 

159,360,000 

5,999,375 

1893 

48,118,000 

1,804,420 

1907 

143,568,000 

6,490,660 

CHAPTER  XVI. 

MANUFACTURE    OF  LEADED  ZINCS. 

242.  History.  The  success  of  the  Eastern  manufacturers 
in  the  manufacture  of  zinc  led  Western  metallurgists  to 
believe  that  a  zinc  oxide  pigment  could  be  prepared  from  the 
complex  Ozark  zinc  ores,  which  are  essentially  the  sulphide, 
carbonates  and  silicates  of  zinc  and  lead.  A  company 
was  formed  for  this  purpose  in  1900,  and  a  plant  with 
four  furnaces  constructed  at  West  Plains,  Mo.,  which 
shortly  afterwards,  however,  proved  too  weak  financially 
to  make  the  experiments  and  improvements  necessary  for 
the  perfecting  of  the  process.  With  the  data  acquired  by 
this  attempt  a  new  company  was  organized  at  St.  Louis, 
and  works  built  near  Joplin,  Mo.,  which  after  numerous 
attempts  succeeded  in  preparing  a  fairly  satisfactory  pig- 
ment. The  success  of  the  project  being  evident,  another 
plant  was  constructed  at  Coffeyville,  Kan.,  which  began 
operations  in  April,  1906.  The  erection  of  the  second 
block  of  furnaces  and  bag-room  was  completed  in  the 
summer  of  1907,  the  plant  now  having  a  capacity  of  about 
sixty  tons  of  ore  daily. 

;  243.  Comparison  with  Eastern  Methods.  The  methods 
used  in  these  plants  differ  considerably  in  details  from  those 
in  use  in  the  Eastern  oxide  plants,  from  the  fact  that  the 
Eastern  ores  are  substantially  free  from  lead,  while  the 
Western  ores  contain  varying  amounts,  ranging  from  three 
to  twenty  per  cent.  Also  anthracite  coal  or  coke  is  used 
for  the  furnace  fuel  in  the  East,  while  soft  or  semi-anthracite 
coal  is  almost  entirely  used  for  the  manufacture  of  Western 

182 


MANUFACTURE  OF   LEADED   ZINCS.  183 

zinc  oxides.  The  hydrocarbons  produced  by  the  use  of 
soft  coal  made  it  necessary  to  change  much  of  the  anthra- 
cite process  in  order  to  secure  complete  combustion  so  that 
the  zinc  oxide  would  not  be  discolored. 

244.  Process  of  Manufacture.     All  grades  of  ore  may  be 
used,  from  zinc  ores  containing  no  lead  up  to  ores  contain- 
ing equal  amounts  of  lead  and  zinc,  the  only  requirements 
being  that  the  combined  assay  of  lead  and  zinc  does  not  fall 
below  30  per  cent,  as  ores  having  less  than  30  per  cent  are 
not  profitable  to  work  in  the  furnace.     Usually  the  ores 
can  be  concentrated  so  as  to  bring  the  average  up  to  this 
figure,  or  high  grade  ore  can  be  added  until  the  content  is 
raised  to  the  desired  point.     As  obtained  in  actual  practice 
the  ratio  of  zinc  to  lead  in  the  mixed  ore  is  about  two  to  one. 

245.  The  mixed  ores  are  sized  and  roasted- in  McDougall 
furnaces  to  a  proper  sulphur  content,  the  amount  of  sulphur 
left  in  the  ore  depending  on  the  amount  required  to  com- 
bine with  the  lead  to  form  sulphate  of  lead.    The  roasted 
ore  is  then  taken  to  the  pigment  furnaces,  of  which  there 

'are  2  blocks  of  18  furnaces  each,  at  the  Coffeyville  works, 
the  size  of  the  individual  furnaces  being  6  feet  by  12  feet. 
The  grates  are  perforated  in  the  usual  manner,  i.e., 
with  conical  holes,  having  a  diameter  of  one-eighth  inch 
at  the  top,  the  holes  being  one  and  one-half  inches  apart. 
The  furnaces  are  charged  with  a  thin  layer  of  semi-anthra- 
cite coal,  common  to  that  section  of  the  country,  and  when 
this  is  burning  freely,  the  mixed  charge  of  ore  and  coal  is 
distributed  evenly  over  the  grate.  The  zinc  oxide  and  lead 
sulphate  pass  off  as  a  fume,  under  carefully  regulated  con- 
ditions, through  several  hundred  feet  of  cooling  pipe,  which 
makes  a  large  horse-shoe  turn,  as  illustrated,  conveying 
the  fume  to  the  bag-room,  where  it  is  collected  in  muslin 
bags  in  much  the  same  manner  as  in  the  Eastern  plants. 
This  process  requires  about  one  hundred  and  fifty  square 


184 


THE   LEAD  AND   ZINC  PIGMENTS. 


MANUFACTURE  OF   LEADED   ZINCS. 


185 


feet  of  muslin  in  the  bag-room  for  every  square  foot  of  grate 
surface  in  the  pigment  furnaces.  The  coarser  particles  of 
the  sublimate  are  deposited  in  the  cooling  pipe,  which  is 
provided  with  cleanout  doors  at  regular  intervals,  as  shown 
in  the  illustration. 

246.  Characteristics.  The  samples  of  oxide  produced  by 
this  process  that  have  been  examined  by  the  writer  were 
not  as  white  as  the  New  Jersey  oxides,  and  are  liable  to 
contain  considerable  amounts  of  zinc  sulphate  and  sulphur 
dioxide,  the  bad  effects  of  which  are  well  known  to  the  paint 
trade,  and  have  been  discussed  to  some  extent  in  other  por- 
tions of  this  book.  The  following  analyses,  made  at  different 
times  by  the  author,  are  believed  to  be  representative  of 
zinc-lead  pigments  of  this  type,  although  the  source  of  these 
samples  was  not  known  to  an  absolute  certainty. 


I. 

II. 

III. 

Moisture  

Per  cent. 
0  03 

Per  cent. 
0  02 

Per  cent. 
0  04 

•Sulphur  dioxide  

0  30 

0  29 

0  50 

Zinc  sulphate  

0  86 

1   49 

1   26 

Lead  sulphate  

26.46 

19  76 

23  06 

Zinc  oxide 

72  11 

78  11 

74  72 

Undetermined 

0  24 

0  33 

0  42 

100.00 

100.00 

100.00 

247.  The  above  figures  indicate  that  the  furnace  charges 
were  not  prepared  as  carefully  with  regard  to  the  lead  and 
zinc  content  as  would  have  been  expected.  In  the  recent 
analyses  made  by  the  writer  on  "  zinc  lead  white  "  the 
writer  has  seldom  found  the  lead  or  zinc  content  to  vary 
more  than  three  per  cent.  As  several  of  the  leading  paint 
chemists  reject  zinc  pigments  containing  more  than  0.06  per 
cent  of  sulphur  dioxide  and  zinc  sulphate  in  excess  of  one  per 
cent  it  is  probable  that  pigments  typical  of  the  above  anal- 
yses would  be  rejected  as  constituents  of  high  class  paints. 


186 


THE   LEAD   AND   ZINC  PIGMENTS. 


MANUFACTURE   OF   LEADED    ZINCS.  187 

248.  Zinc  Sulphate.    The  preceding  illustration,  Fig.  67, 
which  is  from  a  photograph  taken  by  the  writer,  shows  the 
effect  of  zinc  sulphate  when  in  appreciable  quantity.     This 
test  was  three  coat  work  over  new  pine  clapboards.     The 
paint  employed  was  of  a  lead  color,  the  white  base  of  which 
contained  white  lead,  zinc  oxide,  barytes  and  a  leaded  zinc 
containing  an  excess  of  zinc  sulphate.     The  test  had  been 
under  inspection  for  nine  months,  when  the  phenomenon 
illustrated  manifested  itself.     A  number  of  heavy  dews  pre- 
ceded by  a  long  spell  of  dry  hot  weather  caused  the  forma- 
tion of  numerous  drops  of  moisture  on  the  lower  portions  of 
the  clapboards  each  night,  which  evaporated  during  the 
following  day.     These  drops  of  moisture  soaked  and  pene- 
trated the  paint  film  thoroughly,  and  brought  to  the  surface 
and  left  on  evaporation  a  white  deposit.     A  chemical  ex- 
amination showed  that  this  white  substance  was  a  nearly 
pure  sulphate  of  zinc  which  was  not  as  readily  soluble  in 
water  as  normal  zinc  sulphate,  and  by  further  tests  was 
proved  to  be  a  basic  sulphate. 

249.  Result  on  Life  of  the  Paint.     The  extent  of  the 
deposit  is  evident  from  the  photographic  illustration.     A 
paint  composed  of  the  pigments  enumerated  above  would 
not  have  saponified  the  oil  sufficiently  in  nine  months  to 
render  the  film  sufficiently  porous  for  the  ready  lixiviation 
of  sparingly  soluble  salts  unless  there  was  present  an  astrin- 
gent, as  it  were,  which  had  destroyed  the  vitality  or  life  of 
the  oil.     There  was  nothing  in  the  nature  of  the  drier  or  in 
the  quantity  used  that  might  be  expected  to  cause  such  a 
result,  especially  when  it  is  noted  that  the  white  lead  con- 
stituted less  than  20  per  cent  of  the  pigment.     It  is  evident 
that  a  paint  film  in  which  the  oil  has  lost  its  vitality  cannot 
be  expected  to  give  a  satisfactory  wearing  value,  which 
was  amply  shown  to  be  the  case  in  this  instance  by  the  sub- 
sequent inspections. 


CHAPTER    XVII. 

ZINC   LEAD  WHITE. 

250.  Source.     The  larger  portion  of  the  lead  and  copper 
ores  obtained  in  the  Western  part  of  the  United  States  con- 
tains varying  quantities  of  the  precious  metals,  gold  and 
silver.     The  smelting  and  recovery  of  these  four  metals  by 
well-known  metallurgical  processes  is  a  simple  matter  as 
long  as  the  ores  do  not  carry  appreciable  quantities  of  zinc. 
In  a  large  portion  of  these  ores,  however,  zinc  is  present  in 
considerable  amounts  and  constitutes  one  of  the  greatest 
drawbacks  to  ordinary  smelting  methods.     The  reason  for 
this  is  that  no  smelting  method  has  yet    been   devised 
whereby  zinc  can  be  satisfactorily  reduced  and  collected 
simultaneously  with  either  lead  or  copper. 

251.  In  the  ordinary  methods  of  smelting  any  zinc  pres- 
ent in  the  ores  is  entirely  lost  by  volatilization.     This  loss, 
while  serious,  is  not  of  so  much  importance  as  the  difficulty 
encountered  in  freeing  the  ore  from  it.     As  is  well  known, 
all  the  substances  entering  into  a  smelting  furnace  charge 
must  be  reduced  and  collected  in  metallic  form,  melted  to  a 
fluid  slag  which  goes  to  waste,  or  burned  to  gases  which 
escape,  as  is  the  case  with  the  coke.     Zinc   is  extremely 
volatile  at  the  comparatively  high  temperature  necessary 
for  ordinary  furnace  operations,  and  if  the  zinc  is  allowed  to 
volatilize  and  escape  in  this  manner,  the  losses  of  gold  and 
silver  are  such  as  to  render  the  process  unprofitable.     Hence 
the  only  course  left  is  to  convert  the  zinc  into  the  oxide  and 
then  have  it  taken  up  by  the  slag,  which  is  often  a  very 
unsatisfactory  solution  of  the  problem,  as  the  zinc  is  taken 

188 


ZINC   LEAD    WHITE.  189 

up  only  with  difficulty,  resulting  in  the  lengthening  of  the 
furnace  operations  and  in  considerable  increased  cost  of 
slag  material  and  fuel.  It  also  causes  a  serious  loss  of  other 
metals  present,  as  a  zinc  slag  is  not  as  clean  as  one  with- 
out zinc. 

252.  Early  Manufacture.     The   facts   above  cited  ren- 
dered it  impossible  to  treat  the  low  grade  complex  gold 
ores,  which  are  obtainable  in  enormous  quantity  in   the 
Rocky    Mountain    region,    by    the    ordinary    methods    of 
smelting.     The  obvious  solution  of  the  problem  was  the 
successful  removal  of  the  zinc.    This  was  accomplished 
by  the  American  Zinc  Lead  Company,  who  constructed  a 
small  plant  in  Canon  City,  Colorado,  commencing  operations 
in  the  spring  of  1891.     The  metallurgical  methods  used  in 
this  plant  were  in  many  ways  the  reverse  of  ordinary 
methods,  the  zinc  and  lead  being  removed  as  the  first  step 
by  volatilization  as  a  "  fume  "  which  was  collected  and  put 
on  the  market  as  paint  pigment  under  the  name  of  zinc 
lead  white.     This  process  left  the  copper,  gold  and  silver 
in  the  furnace  cinder,  which  was  then  smelted  out  in  the 
regular  way. 

253.  Absorption   by   United   States   Smelting   Company. 
At  the  inception  of  the  industry,  the  pigment  obtained, 
i.e.,  the  zinc  lead  white,  was  considered  as  a  by-product 
and  of  minor  importance,  the  profitable  recovery  of  the 
copper,  gold  and  silver  being  the  main  object;  consequently 
little  regard  was  paid  to  the  varying  proportions  of  the 
volatile   constituents  —  zinc    and   lead  —  and    hence   the 
pigment  varied  constantly  in  composition  and  color.     In 
1902,  the  plant  process  and  patents  were  taken  over  by 
the   United   States   Smelting    Company    and    the    plant 
enlarged  greatly. 

254.  Standard    of    Composition.   In    order    to    obviate 
variations  in  composition  as  far  as  possible,  a  standard  of 


190 


THE  LEAD   AND   ZINC  PIGMENTS. 


ZINC   LEAD   WHITE.  191 

proportional  contents  of  lead  and  zinc  was  adopted  for  the 
pigment  and  the  charges  of  ore  were  prepared  for  furnacing 
on  the  basis  of  chemical  analysis,  resulting  in  the  produc- 
tion of  a  pigment  which  runs  approximately  fifty  per  cent 
zinc  oxide  and  fifty  per  cent  lead  sulphate.  The  ores  and 
concentrates  operated  on,  while  low  in  gold  and  silver,  are 
high  in  the  zinc  and  lead  content,  even  higher  than  the 
average  lead  and  zinc  ores. 

255.  Sublimation  of  Fume.   The  ore  on  receipt  at  the 
works  is  crushed  and  screened  by  suitable  machinery  and 
mixed  in  such  proportions  as  will  yield  the  desired  ratio  of 
zinc  and  lead  in  the  finished  pigment.     The  ore  is  then 
fed,  together  with  a  sufficient  amount  of  fine  coal  or  coke, 
into  the  volatilizing  and  oxidizing  furnaces,  which  are  so 
constructed  as  to  admit  air  to  the  incandescent  mass  of 
ore  and  fuel  on  the  grates,  in  proper  supply  and  from  all 
sides.     The  zinc  and  lead  present  is  reduced  to  the  metallic 
state,  and  instantly  vaporized  and  drawn  by  the  exhaust 
fans  into  combustion  chambers  where  oxidation  takes  place, 
the  zinc  being  converted  into  zinc  oxide  and  the  lead  to 
lead  sulphate. 

256.  Collection  of  Fume.     These    two  products,   being 
formed  from  a  homogeneous  gas  into  minute  solid  particles, 
are  most  closely  associated  together,  existing  in  almost  as 
close  a  union  as  though  chemically  combined.     By  reason 
of  the  suction  fans,  these  minute  particles,  in  the  form  of  a 
white  fume,  are  carried  along  through  a  series  of  cooling 
flues  to  suspended  woolen  collecting  bags  through  which 
the  sulphurous  gases  of  the  combustion  pass,  while  the 
pigment  is  retained. 

257.  Final  Treatment.   The  white  pigment  as  it  collects 
in  quantity  is  removed  from  these  bags  and  carried  to  the 
finishing  furnaces  where  on  open  hearths,  charged  and  dis- 
charged continuously,  the  crude  product  is  further  oxidized, 


192 


THE  LEAD  AND   ZINC  PIGMENTS. 


ZINC   LEAD   WHITE. 


193 


194 


THE  LEAD  AND   ZINC  PIGMENTS. 


condensed  in  bulk,  desulphurized  and  whitened.  Finally, 
the  finished  product  is  bolted  through  a  fine  cloth  screen 
and  packed  for  shipment. 

258.  Production.  In  1892,  about  24,000,000  pounds  of 
low  grade  sulphide  ore  were  treated  by  this  process,  pro- 
ducing 2,500,000  pounds  of  zinc  lead  white,  360,000 
pounds  of  copper,  137,000  ounces  of  silver  and  120  ounces 
of  gold.  The  production  of  zinc  lead  white  increased 
slowly  until  1901,  from  which  date  the  amount  produced 
increased  rapidly,  as  is  shown  in  the  following  table  — 


ZINC   LEAD  WHITE. 


Year. 

Production    in    pounds. 

Value. 

Total. 

Per  Ib. 

1901 
1902 
1903 
1904 
1905 
1906 
1907 

5,000,000 
8,000,000 
9,000,000 
11,558,000 
13,558,000 
16,148,000 
27,032,000 

$150,000 
225,000 
247,500 
404,530 
474,530 
681,292 
1,286,440 

$0.0300 
0.0281 
0.0265 
0.0350 
0.0350 

259.  Physical  Properties.  As  produced,  zinc  lead  white 
is  intermediate  in  its  properties  between  the  lead  and  zinc 
pigments,  resembling  zinc  oxide  perhaps  more  than  lead 
pigments,  for  instance,  sublimed  white  lead,  which  is  pre- 
pared much  in  the  same  way.  The  combination  between 
the  zinc  oxide  and  the  lead  sulphate  is  probably  not  chem- 
ical in  its  nature,  but  may  be  described  as  an  alloy  of  the 
two  pigments,  the  temperature  of  production  being  exceed- 
ingly high,  and  therefore  it  is  to  be  expected  that  the 
pigment  would  possess  the  individual  characteristics  of 
its  components. 


ZINC   LEAD   WHITE. 


195 


FIG.  71.  —  BAG-ROOM,  —  U.  S.  SMELTING  COMPANY. 


196  THE   LEAD   AND   ZINC   PIGMENTS. 

260.  Recent  Improvements.   During  the  last  few  years 
there  has  been  a  marked  improvement  in  its  whiteness 
and  uniformity  of  composition.     The  slight  yellowish-gray 
tint  that  it  possesses  does  not  at  all  interfere  with  its  use 
in  ready  mixed  paints  or  combination  leads.     The  very 
reasonable  price  at  which  this  pigment  has  been  offered  to 
the  trade  has  caused  its  rapid  adoption  by  the  paint  manu- 
facturers, and  there  are  probably  very  few  paint  houses 
who  do  not  find  a  use  for  it  in  some  of  their  products. 

261.  Use  in  House  Paints.   Owing  to  the  uniform  fine- 
ness of  the  pigment  particles  of  zinc  lead  white  it  produces 
a  paint  that  brushes  easily  and  flows  out  evenly,  being  one 
of  the  most  satisfactory  pigments  we  have  in  these  respects. 
As  a  white  base  in  conjunction  with  a  small  percentage  of 
white  lead  and  25  to  40  per  cent  of  zinc  oxide,  for  tinted 
house  paints  zinc  lead  white  has  found  a  wide  use.     White 
lead,  i.e.,  basic  carbonate  of  lead,  owing  to  its  lack  of  chem- 
ical stability,  is  particularly  unsuited  for  the  production  of 
tints   containing   chrome   yellow,   Prussian   blue,   chrome 
green  and  ultramarine  blue  owing  to  chemical  interaction 
of  these  colors  with  the  white  lead  causing  a  fading  or 
darkening  of  the  paint  film  as  the  case  may  be.     The 
sulphates  of  lead,  including  the  basic  lead  sulphate  produced 
by  the  Picher  Lead  Company,  have  a  much  more  stable 
constitution  and  are  not  easily  affected  by  the  tinting 
colors  with  which  they  may  be  used,  and  this,  to  the  paint 
manufacturer,  is  a  very  serious  consideration. 

262.  Use  in  the  Manufacturing  Trades.   Zinc  lead  white 
finds  perhaps  its  greatest  use  in  paints  for  the  manufac- 
turing trades  such  as  paints  for  farm  implements,  farm 
machinery,  etc.,  especially  where  dipping  is  resorted  to, 
i.e.,  the  articles  to  be  painted  are  dipped  in  large  tanks 
of  the  prepared  paint  and  the  surplus  paint  allowed  to 
drain  off.     In  order  for  this  operation  to  be  uniformly 


ZINC   LEAD   WHITE. 


197 


198  THE  LEAD   AND   ZINC  PIGMENTS. 

successful  it  is  necessary  to  use  pigments  which  in  addition 
to  possessing  the  requisite  body  or  hiding  power  must  be 
non-settling  in  the  rather  thin  vehicle  employed.  Zinc 
lead  white  meets  these  combined  requirements  excellently 
and  is  therefore  almost  universally  used  for  this  line  of 
paints. 

263.  There  has  been  some  complaint  in  the  past  regard- 
ing the  amount  of  arsenic  present  as  an  impurity  in  zinc 
lead  white;  at  the  present  time,  however,  the  arsenic  can 
be  considered  as  a  negligible  factor  as  it  is  usually  less  than 
0.20  per  cent,  while  New  Jersey  zinc  oxide  often  contains 
0.08  per  cent  and  is  used  in  far  greater  quantities  and  in 
higher  percentages  for  interior  work  than  zinc  lead  white. 

264.  Chemical   Composition.   There  has   been   more   or 
less  claim  that  the  lead  in  zinc  lead  white  is  in  the  form  of 
an  oxysulphate,  but  a  careful  comparison  of  the  combined 
sulphuric  acid  with  the  amount  of  lead  does  not  justify 
this   view.     Naturally    under   certain    furnace    conditions 
a  small  amount  of  oxysulphate  may  be  formed,  but  the 
writer  has  never  been  able  to  find  more  than  a  fraction  of 
one  per  cent.     Being  the  product  of  a  complex  metallurgi- 
cal operation  it  is  to  be  expected  that  zinc  lead  white  will 
vary   slightly   in   composition   even   though   the   furnace 
charge  is  prepared  on  the  basis  of  a  chemical  analysis  so  as 
to  yield  a  pigment  half  lead  sulphate  and  half  zinc  oxide. 
As  above  mentioned  zinc  sulphate  is  the  leading  impurity 
and  owing  to  the  nature  of  the  process  will  always  be 
present  in  a  greater  or  less  quantity,  but  with  care  can  be 
kept  to  below  one  per  cent,  which  is  the  limit  set  by  several 
leading  paint  chemists.     Considering  the  price  at  which  this 
pigment  is  offered  for  sale  it  is  one  of  the  most  acceptable 
paint  pigments  at  the  command  of  the  paint  manufacturer. 

265.  Zinc  Sulphate.   Used  in  outside  house  paints  zinc 
lead  white  has  caused  some  complaint  due  to  the  "  washing  " 


ZINC   LEAD   WHITE.  199 

of  the  paint  film,  a  condition  better  observed  than  des- 
cribed, seeming  to  consist  in  the  washing  away  of  the  pig- 
ment particles  from  the  binder,  causing  either  a  streaked  or 
faded  appearance  of  the  paint  film.  This  effect  is  appar- 
ently due  to  the  presence  of  zinc  sulphate  in  the  pigment, 
although  the  exact  manner  in  which  the  action  takes 
place  is  not  clear.  Some  paint  chemists  have  claimed 
that  it  was  due  to  the  astringent  action  of  sulphur  dioxide 
on  the  linseed  oil,  but  as  a  matter  of  fact  zinc  lead  white 
contains  less  than  0.01  per  cent  of  sulphur  dioxide,  being 
purer  in  this  respect  than  the  New  Jersey  zinc  oxides. 
In  an  extensive  practical  test  conducted  by  the  writer  at 
the  North  Dakota  Experiment  Station,  three  ready  mixed 
paints  were  applied,  one  of  which  was  composed  of  straight 
zinc  lead  white ;  the  second  contained  about  50  per  cent  of 
a  leaded  zinc  from  a  different  source,  which  in  addition 
to  zinc  sulphate  contained  a  considerable  amount  of  sul- 
phur dioxide;  the  third  contained  about  forty  per  cent  of 
zinc  lead  white.  All  three  paints  washed  noticeably  inside 
the  first  twelve  months  exposure,  but  the  second  paint, 
containing  the  sulphur  dioxide,  did  not  wash  to  any  greater 
extent  than  did  paint  number  three.  The  straight  zinc 
lead  white  "  washed  "  the  most  seriously  of  all,  which 
indicated  that  the  presence  of  other  pigments  restrained 
the  "  washing  "  to  some  extent. 

266.  This  "  washing,"  however,  does  not  seem  to  be 
accompanied  by  any  marked  cracking,  peeling,  or  chalk- 
ing, providing  the  paint  has  been  suitably  applied,  and 
such  paint  usually  wears  down  to  a  uniform  surface 
excellent  for  repainting. 


CHAPTER  XVIII. 

THE   OXIDES  OF  LEAD. 

267.  Classification.   Lead    forms   five   compounds   with 
oxygen,  as  follows: 

Pb20,  lead  suboxide, 

PbO,  lead  monoxide, 

Pb02,  lead  dioxide, 

Pb203,  lead  sesquioxide,  and 

Pb304,  red  lead,  orange  mineral. 

268.  Not  all  of  these  forms  find  commercial  uses,  however, 
notably   the  suboxide  and   sesquioxide.     The  dioxide  is 
used  only  to  a  limited  extent,  chiefly  for  electrical  pur- 
poses.    The  monoxide,  known   under  the  two   varieties, 
litharge   and   massicot,   is   produced   in   large   quantities. 
The  other  oxide,  which  corresponds  quite  closely  to  the 
empirical  formula  Pb304,  is  also  placed  on  the  market  in 
two  modifications  —  red  lead,  sometimes  known  as  minium, 
and    orange    mineral.      Regarding    the    relation    existing 
between  red  lead  and  the  other  oxides  of  lead  nothing 
definite  can  be  stated.     Numerous  chemists  regard  it  as  a 
mixture    of    the   monoxide    and  dioxide  (2PbO  +  Pb02), 
but  perhaps  the  majority  of  authorities  consider  that  the 
evidence  leads  to  the  conclusion  that  it  is  a  chemical  com- 
pound and  not  a  mixture. 

269.  Lead  Suboxide.    This  compound  is  formed  when 
lead  is  exposed  to  air  under  certain  conditions  as  when  lead 
is  atomized  with  a  jet  of  steam  as  carried  out  in  both  the 
Carter  and  Mild  process,  the  little  particles  of  lead  being 

200 


THE  OXIDES  OF  LEAD. 


201 


covered  with  a  coating  of  the  suboxide.  As  prepared  it  is 
black,  but  in  moist  condition  is  very  susceptible  to  further 
oxidation. 

270.  Litharge  (lead  monoxide).  The  transformation  of 
lead  into  a  dry  powder  which  we  know  as  litharge,  by  expos- 
ing it  to  the  action  of  heat,  was  known  to  the  ancients,  and 
was  without  doubt  the  first  of  the  lead  compounds  known 


FIG.  73.  —  OXIDE  WORKS.  —  MATHESON  &  COMPANY. 

to  them,  and  Napier  states  that  it  has  been  found  in  the 
analyses  made  of  the  paints  and  glazes  used  by  the  ancient 
Egyptians  for  decorating  their  pottery.  Maigue,  in  his  Dic- 
tionnaire  Classique,  states  that  the  art  of  making  litharge 
originated  in  the  East,  and  is  supposed  to  have  been  known 
in  the  time  of  Solomon.  Bricks  and  various  articles  of 
pottery  which  have  been  found  in  the  ruins  of  Nineveh  and 
Babylon  are  believed  to  have  been  glazed  by  the  use  of 
litharge. 


202  THE  LEAD   AND   ZINC  PIGMENTS. 

271.  Early  Confusion  regarding  Nature  of  Litharge.    As 
litharge  occurs  in  several  modifications,  some  of  them  granu- 
lar and  some  flaky,  varying  in  color  from  a  light  golden 
yellow  to  a  buff  color,  it  is  not  to  be  wondered  at  that  the 
ancient  writers  were  much  confused  in  their  descriptions 
of  the  product  and  the  process  of  manufacture.     Pliny 
apparently  had  some  definite  knowledge  of  this  product, 
which  he  discusses  under  the  name  of  "  molybdena,"  stat- 
ing,  "It  is  considered  better  in  quality,  the  nearer  it 
approaches  golden  in  color,  and  the  less  lead  it  contains 
(probably  referring  to  metallic  particles);  it  is  also  friable 
and  of  moderate  weight;  it  is  found  adhering  to  furnaces  in 
which  gold  and  silver  have  been  smelted."     Later  Dis- 
corides  in  discussing  products  made  from  lead  states  that  a 
more  difficult  way  of  producing  litharge  is  "  burning  the 
lead  without  admixture  of  any  other  substance."     This  is 
undoubtedly  the  earliest  reference  to  the  production  of 
litharge  from  lead  as  a  primary  product. 

272.  Development    of   Litharge    Industry.    The   use   of 
litharge  did  not  develop  rapidly  and  it  remained  an  article 
of  comparative  unimportance  for  a  great  many  centuries. 
In  the  manuscripts  of  the  Middle  Ages  it  is  mentioned 
rarely,  and  probably  did  not  begin  to  find  favor  until  about 
the  fifteenth  century.     With  the  development  of  the  white 
lead  industry  by  the  Dutch,  it  is  only  natural  they  should 
have  attempted  the  manufacture  of  litharge  and  red  lead 
on  a  comparatively  large  scale,  but  as  far  as  litharge  was 
concerned  they  did  not  meet  with  any  great  financial  suc- 
cess, owing  to  their  disadvantageous  location,  having  to 
import  their  lead  from  countries  where  litharge  was  pro- 
duced as  a  by-product,  as  in  the  seventeenth  century  we 
find  the  English  exporting  litharge  in  large  quantities  to  all 
parts  of  Europe,  it  being  obtained  by  them  in  refining  of 
their  argentiferous  ores. 


THE  OXIDES  OF   LEAD. 


203 


204  THE   LEAD  AND   ZINC  PIGMENTS. 

273.  Manufacture.    As  an  article  of  direct  production, 
litharge  is  prepared  in  this  country  by  two  processes  which 
are  the  same  in  principle,  but  are  quite  different  mechan- 
ically.    In  the  older  and  more  general  process  the  lead  is 
placed  in  a  low  arched  reverberatory  furnace,  the  fire  being 
on  one  side  and  separated  from  the  melting  hearth  by  a  low 
brick  wall,  causing  the  flame  and  heat  to  pass  above  the  sur- 
face of  the  lead.    A  rapid  oxidation  ensues,  the  oxide  being 
pushed  to  one  side  by  means  of  an  iron  rabble,  thus  exposing 
a  fresh  surface  of  the  lead  to  oxidation.     Pigs  of  lead  are 
gradually  added  and  the  operation  continued  until  a  suffi- 
cient amount  of  oxide  is  accumulated,  which  is  then  with- 
drawn   from    the   furnace,    ground    and   levigated.      The 
oxidizing  operation  is  conducted  at  or  above  the  melting 
point  of  the  litharge.     As  produced  by  this  process  litharge 
is  a  buff-colored  powder. 

274.  Cupellation  Process.     The  other  process  attains  the 
same  result  by  the  use  of  natural  gas,  and  air  jets  play  over 
the  surface  in  such  a  manner  as  to  sweep  the  molten  oxide 
as  it  is  formed  toward  the  front  of  the  furnace,  and  by  regu- 
lating the  size  of  the  stream  of  molten  lead  which  is  con- 
stantly flowing  in,  the  molten  oxide  flows  over  the  lip  of  the 
basin  in  a  steady  stream  into  a  conical  shaped  iron  container 
mounted  on  trucks,  which  when  full  is  hauled  away  to  cool, 
after  which  the  contents  are  removed  by  inverting  the  con- 
tainer; the  cake  is  then  broken  up  with  sledge  hammers, 
ground  and  air-floated  to  free  it  from  metallic  lead  particles. 

275.  Other  Processes.     As  an  indirect  product,  litharge 
is  produced  in  the  metallurgy  of  silver,  the  resulting  alloy  of 
lead  and  silver  being  subjected  to  oxidation  whereby  the 
lead  is  converted  into  litharge,  the  silver  remaining  in  the 
metallic  condition,  and  is  so  removed.     The  production  of 
litharge  from  acetate  of  lead  and  residual  metallics  has 
already  been  discussed  under  the  Matheson  process.    This 


THE  OXIDES   OF   LEAD.  205 

litharge  is  entirely  free  from  metallics.  Sublimed  litharge 
has  also  been  mentioned  in  connection  with  the  sublimed 
lead  pigments. 

276.  Properties.     As   it   occurs   in    commerce,    litharge 
usually  contains  iron,  copper,  and  a  little  silver  and  silica, 
as  well  an  an  appreciable  percentage  of  metallic  lead.   Some- 
times it  will  be  found  to  contain  lead  carbonate  and  sulphate. 
If  the  heat  has  not  been  carefully  regulated,  it  will  contain 
quite  a  little  red  lead,  which  is  a  serious  objection  from  the 
color  maker's  point  of  view,  as  the  red  lead  is  insoluble  in 
the  acetic  acid  which  is  the  solvent  acid  for  the  lead  in  most 
instances  in  making  chrome  yellows  and  chrome  greens. 
Litharge  for  storage  battery  use  must  be  free  from  metallic 
lead  and  should  not  contain  more  than  0.006  per  cent  of 
chlorine. 

277.  Massicot.     This   oxide   has   apparently    the   same 
chemical  composition  as  litharge.     It  is,  however,  much 
different  in  its  physical  properties,  and  to  some  extent  in 
its  chemical  properties.     It  is  the  product  of  the  first  stage 
of  the  manufacture  of  red  lead  by  the  double  firing  method, 
and  its  method  of  preparation  will  be  found  under  that  head- 
ing.    It  is  a  pale  greenish  yellow  powder  of  granular  texture. 

278.  Commercial  Classification.    Commercially  the  differ- 
ent modifications  of  litharge  of  lead  monoxide  are  known  as 

Color  makers'  oxides. 
Enamelers'  oxides. 
Glassmakers'  oxides. 
Potters'  oxides. 
Rubber  makers'  oxides. 
Varnish  makers'  oxides. 

279.  These  terms,   however,   have  partially  lost  their 
original  significance,  as  the  quality  of  oxide  obtained  in  any 
of  these  industries  will  depend  to  a  considerable  extent  on 
the   discrimination   exercised    by   the   purchaser.     Color- 


200 


THE   LEAD   AND   ZINC  PIGMENTS. 


makers'  oxide  is  a  crystalline  oxide  ground  very  fine,  is 
or  should  be  free  from  metallic  lead  and  entirely  soluble  in 
dilute  acetic  acid.  One  of  the  leading  brands  of  color- 
makers'  litharge  analyzed  by  the  author  gave  only  0.18 
per  cent  insoluble  impurities  in  acetic  acid.  A  more  finely 
powdered  sample  of  the  same  brand  gave  0.70  per  cent 
insoluble.  Enamelers',  glassmakers'  and  potters'  oxides  are 
usually  the  more  common  grades,  although  the  purchaser 
may  not  always  be  aware  of  the  fact.  Iron  and  copper 
are  the  most  serious  impurities.  Rubber  makers'  oxide  is 
also  a  common  oxide  although  the  metallic  lead  is  kept  as 
low  as  possible.  Varnish  makers'  oxide  should  be  as  free 
as  possible  from  red  lead.  It  usually  contains  a  small 
amount  of  metallics. 

280.  Production  of  Litharge  in  the  United  States.  The 
following  figures,  taken  from  the  Mineral  Resources  of  the 
United  States,  give  some  idea  of  the  importance  that 
the  manufacture  of  this  lead  product  has  assumed. 


Year. 

Quantity. 

Value. 

1902 
1903 
1904 
1905 
1906 
1907 

Ibs. 
25,510,690 
20,342,000 
16,724,44s1 
39,756,000  l 
37,820,000  l 
41,676,000 

$1,298,343 
1,116,361 
922,919 
2,307,233 
2,551,346 
2,854,987 

1  Includes  production  of  orange  mineral. 

281.  Imports.  A  comparison  with  the  amounts  imported 
during  this  period  indicates  that  the  litharge  industry  is 
fully  equal  to  domestic  consumption. 


Year. 

Quantity. 

Value. 

1902 
1903 
1904 
1905 
1906 
1907 

Ibs. 
88,115 
42,756 
44,541 
117,757 
87,230 
90,475 

$2,908 
1,464 
1,500 
4,139 
3,737 
4,386 

CHAPTER  XIX. 

THE   OXIDES  OF  LEAD    (Continued). 

282.  Early  History  of  Red  Lead.   Red  lead  and  orange 
mineral,  while  not  of  as  ancient  origin  as  litharge,  were 
well  known   to   the   early  Greeks   and  Romans.     Orange 
mineral,  which  may  be  considered  as  a  variety  of  red  lead, 
was  a  well  known  product  in  the  time  of  Pliny,  who  relates 
that  it  was  discovered  by  accident  through  the  occurrence 
of  a  fire  in  a  house  near  Athens,  containing  several  earthen 
jars  filled  with  white  lead,  it  being  alleged  that  the  white 
lead  or  ceruse  was  in  the  apartments  of  a  lady  who  was 
accustomed  to  use  it  as  a  cosmetic.     After  the  fire  it  was 
found  to  have  been  changed  in  color  to  a  brilliant  scarlet 
red  and  was  afterwards  used  by  Nicias,  a  celebrated  artist 
who  lived  about  320  B.C.,  as  a  new  pigment,  and  was  after- 
wards known  under  the  name  cerussa  usta. 

283.  Early  Methods  of  Preparation.   The  preparation  of 
red  lead  by  first  drossing  lead  at  a  low  temperature  and 
then   reheating  the   litharge   or  massicot   thus   obtained, 
seems  to  have  been  unknown  to  the  ancients  as   they 
depended  entirely  on  the  product  obtained   by  heating 
white  lead,  which  according  to  Discorides  should  be  "  put 
in  a  new  earthen  vessel,  best  of  all  an  Attic  one,  over  coals, 
sprinkle  in  it  powdered  ceruse,  stir  constantly,  and  when 
it  shall  have  acquired  the  color  of  ashes,  remove  and  cool 
and  so  use  it.     But  if  you  desire  to  burn  it,  place  it  pow- 
dered in  a  hollow  platter,  and  having  set  this  on  the  coals, 
stir  with  an  iron  rod  until  it  attains  the  color  of  sanda- 
rach;  then  take  it  out  and  use." 

207 


208  THE  LEAD   AND   ZINC  PIGMENTS. 

284.  The  presence  of  red  lead  has  been  found  in  several 
analyses  by  Davy  of  colors  obtained  from  the  ruins  of 
ancient  Rome.     Its  use,  however,  by  artists  was  slight  and 
unimportant  down  to  the  time  of  the  revival  of  art  in  Italy. 
But  from  this  period  its  use  and  manufacture  rapidly  spread 
over  Western  Europe. 

285.  Development    of   the    Industry.    History   does   not 
clearly  record  the  time  that  our  present  method  of  making 
red  lead,  i.e.,  of  first  dressing  the  metal  and  then  reheating 
the  oxide  produced,  first  came  into  use,  but  it  was  probably 
prior  to  the  beginning  of  the  sixteenth  century.     It  is 
recorded  that  as  early  as  1622,  there  were  at  least  four 
firms  engaged  in  the  manufacture  of  red  lead  or  minium 
in    England.     Smith    in    his    "  Painting   in    Oyl,"    1676, 
describes  the  dressing  of  lead,  forming  litharge  which  is 
then  treated  in  a  furnace  with  constant  stirring.     He  also 
adds  that  this  red  lead  thus  produced  is  used  in  the  manu- 
facture of  drying  oils. 

286.  Savary,  in  his  Universal  Dictionary  (1751)  gives  a 
comprehensive  description  of  the  manufacture  of  red  lead, 
showing  that  the  underlying  principles  were  well  under- 
stood at  that  time.     According  to  his  description  the  lead 
was  melted  in  a  broad,  shallow,  open  vessel,  stirred  until 
reduced   to  a  gray  powder,  which  on   further  treatment 
became  the  product  known  as  "  masticot."     This  masti- 
cot  was  then  heated  in  a  reverberatory  furnace  where  it 
changed  its  hue  to  a  fine  red  color  and  became  minium 
or  red  lead.     By  this  time  red  lead  had  become  a  common 
article  of  commerce  and  was  being  produced  in  quite  large 
quantities  by  those  accustomed  to  the  manufacture  of  white 
lead,  especially  among  the  Dutch  and  English. 

287.  Early  Manufacture  in  the  United  States.   The  exact 
date  of  the  beginning  of  the  red  lead  and  litharge  industry 
in  the  United  States  is  not  known,  but  probably  preceded 


THE   OXIDES   OF   LEAD.  209 

that  of  the  manufacture  of  white  lead  by  a  very  brief 
interval.  Bishop  relates  that  there  were  three  red  lead 
works  in  operation  in  Philadelphia  as  early  as  1810.  The 
oxide  industry,  however,  is  so  closely  associated  with  the 
manufacture  of  white  lead  that  it  has  almost  entirely  passed 
into  the  hands  of  the  latter  and  there  are  at  the  present 
time  only  one  or  two  firms  who  are  engaged  in  the  manu- 
facture of  oxides  who  are  not  making  white  lead. 

288.  Present  Methods  of  Manufacture.    By  far  the  greater 
portion  of  red  lead  manufactured  in  this  country  is  made  by 
the  two  stage  method.    The  first  stage,  which  consists  of  the 
dressing  of  the  lead,  is  conducted  in  a  reverberatory  furnace 
with  free  access  of  air.     The-  heat  is  generated  usually  in 
two  fireplaces,  arranged  one  on  each  side  of  the  rectangular 
dressing  basin  and  are  separated  from  it  by  means  of  low 
walls  so  that  the  flame  and  heated  products  of  combustion 
do  not  come  in  close  contact  with  the  surface  of  the  lead 
but  pass  close  to  the  vault  of  the  furnace,  the  lead  being 
heated  by  the  reflected  heat  from  the  vault,  the  various 
gases  passing  off  through  a  flue  situated  over  or  at  one  end 
of  the  dressing  basin. 

289.  Furnace    Temperature.     The    temperature    of    the 
furnace  must  be  kept  within  certain  narrow  limits,  slightly 
above  the  melting  point  of  lead,  i.e.,  about  340°  C.,  for  if 
the  oxide  formed,  which  is  known  as  massicot,  is  allowed 
to  melt  it  undergoes  a  molecular  change  and  becomes  the 
ordinary  litharge,  which,  as  is  well  known,  is  a  fixed  oxide 
and  will  not  take  up  oxygen  and  become  red  lead  in  the 
second  or  calcining  stage. 

290.  The  bottom  of  the  furnace  or  dressing  basin  is  more 
or  less  concave,  although  the  low  level  is  maintained  to  the 
bottom  of  the  door  at  the  front  of  the  furnace  to  permit  of 
the  easy  removal  of  unoxidized  lead  remaining  at  the  end 
of  the  dressing  stage. 


210 


THE   LEAD   AND   ZINC   PIGMENTS. 


THE   OXIDES   OF   LEAD.  211 

291.  Dressing.     The  furnace  is  raised  nearly  or  quite  to 
a  very  dull  red  heat,  several  hundred  weight  of  pig  lead 
introduced,  the  molten  metal  as  it  forms  being  prevented 
from  flowing  out  of  the  front  of  the  furnace  by  a  dam  of 
dross  obtained  from  a  preceding  charge.     The  molten  lead 
becomes  rapidly  coated  with  a  pellicle  of  oxide,  which  is 
raked  to  the  front  or  back  of  the  furnace  by  means  of  a 
heavy  long-handled  iron  rake  suspended  by  a  chain  from 
overhead  so  as  to  permit  of  easy  manipulation.     At  inter- 
vals more  lead  is  introduced  into  the  furnace  and  the  dross- 
ing  operation  continued  for  about  twenty-four  hours,  suffi- 
cient air  being  introduced  through  the  door  in  front.     The 
unoxidized  lead,  which  may  constitute  15  to  30  per  cent  of 
the  furnace  charge,  is  then  allowed  to  run  off,  and  the  massi- 
cot, which  forms  a  friable  yellow  or  greenish  yellow  mass 
and  corresponds  to  the  formula  PbO,  is  raked  out  into  iron 
carts,  cooled,  ground  and  floated  to  free  it  from  metallic  par- 
ticles, dried  and  introduced  into  the  calcining  furnaces,  which 
are  similar  to  the  dressing  furnaces  or  else  of  the  muffle 
type.     The  collected  residues,  consisting  of  coarse  dross  and 
granules  of  metallic  lead,  amounting  to  from  10  to  30  per 
cent  of  the  furnace  charge,  are  dried  and  again  drossed. 

292.  Coloring.     For  the  production  of  the  deepest  red 
tones  a  muffle  furnace  is  used,  for  if  the  flame  is  allowed  to 
come  in  contact  with  the  product,  the  tint  is  injured.     A 
suitable  current  of  air  is  admitted  and  the  mass  frequently 
raked  in  order  to  assist  the  absorption  of  oxygen  and  to 
develop  the  tint,  the  operation  requiring  upwards  of  forty- 
eight  hours,  samples  being  taken  at  intervals  until  the 
desired  tint  is  obtained.    The  red  lead  is  then  removed, 
cooled,  and  if  not  sufficiently  fine,  is  ground.     As  in  the 
dressing  stage,  the  temperature  in  the  second  or  calcining 
stage  must  be  carefully  regulated  and  kept  within  certain 
narrow  limits, 


212  THE   LEAD    AND    ZINC  PIGMENTS. 

293.  The    brightness,  deepness,  and    beauty    of    color 
depend  on  the  care  exercised  in  calcining  and  are  not  wholly 
influenced  by  the  absorption  of  oxygen,  but  more  especially 
by  the  particular  molecular  condition  or  structure  of  the 
product,  and  this  is  only  obtained  within  a  certain  narrow 
range  of  temperature. 

294.  Modern  Improvements.     Various  modifications  have 
been  developed  which  have  simplified  and  shortened  the 
furnacing  operation  as  applied  to  red  lead  and  also  litharge. 
They  have  not,  however,  proven  sufficiently  economical  as 
to   have  materially   restricted   the   use  of   the  two-stage 
process.     Among    these    various    improvements    may    be 
mentioned  the  use  of  mechanical  stirrers,  rotary  dressing 
furnaces,  use  of  currents  of  superheated  air,  etc. 

One  modification,  however,  has  proven  financially  suc- 
cessful, owing  to  the  production  of  a  valuable  by-product, 
nitrite  of  soda,  much  used  as  a  diazotizing  agent  in  the 
manufacture  of  para  reds  and  other  similar  colors.  This 
modification  is  based  on  the  fact  that  sodium  nitrate  will 
easily  give  up  one  atom  of  oxygen,  becoming  sodium 
nitrite  and  the  liberated  oxygen  immediately  combining 
with  metallic  lead  to  form  an  oxide  easily  convertible  into 
red  lead,  or  it  may  be  made  to  convert  massicot  rapidly 
into  red  lead,  according  to  the  following  equation : 

3  PbO  +  NaN03  =  Pb304  +  NaNO2. 

295.  The  Nitrate  Process.     Many  types  of  furnaces  have 
been  designed  in  order  to  bring  about  the  above  reactions. 
In  one  modification  for  the  production  of  a  massicot  or 
litharge  the  sodium  nitrate  is  melted  in  a  large  iron  pot, 
which  is  kept  at  about  340°  C.;  or  at  about  the  melting- 
point  of  lead.    The  lead  is  added  in  the  form  of  thin  plates 
until  in   slight  excess  of  the  calculated   quantity.     The 
temperature  is  kept  up  for  about  20  to  30  minutes  after  all 


THE   OXIDES   OF   LEAD.  213 

of  the  lead  has  been  added,  or  until  the  yellow  mass  has 
turned  to  a  brownish  color.  The  liquid  mass  is  then 
re:n  )ved,  extracted  with  water  to  dissolve  out  the  sodium 
nitrite,  the  solution  of  which  is  evaporated  and  the  nitrite 
crystallized  out.  In  another  modification  a  circular  iron 
pan  about  4  feet  in  diameter  and  18  inches  deep  is  used. 
The  pan  is  provided  with  a  mechanical  stirrer  and  is  placed 
on  a  perforated  arch;  200  pounds  of  nitrate  is  added  and 
when  melted  about  300  pounds  of  lead  added ;  the  mass  is 
then  agitated  until  oxidized,  when  50  pounds  of  nitrate  and 
350  pounds  of  lead  are  added.  The  heat  is  maintained  for 
30  to  45  minutes  after  apparent  action  has  ceased. 

296.  The  molten  contents  are  poured  into  120  gallons  of 
warm  water,  the  sodium  nitrite  going  into  solution.    The 
solution  is  drawn  off  into  a  large  tank,  neutralized  with  just 
sufficient  sulphuric  acid,  the  settled  liquor  concentrated 
in  iron  pans  or  multiple  effect  evaporators  to  about  45°  B., 
and    allowed    to    crystallize.     The    nitrite   thus   obtained 
should  be  at  least  96  per  cent  pure.     The  oxide  is  freed  from 
all  traces  of  nitrite  by  washing  in  an  agitated  washing  box, 
dried  and  treated  as  desired. 

297.  Properties.   When  properly  prepared  red  lead  is  a 
brilliant  scarlet  red  crystalline  powder  containing  90.66 
per  cent   lead  and    9.34  per  cent   oxygen,  the  theoretical 
chemical  increase  in  manufacture  being  10.3  per  cent.     In 
actual  practice,  especially  in  the  double  furnacing  method, 
this  is  not  obtained,  7  to  8  per  cent  representing  the  in- 
crease obtained,  as  there  is  considerable  loss  of  oxide  dust 
through    the   flues."     Its   specific  gravity  varies  between 
8.6  and  9.1.     On  heating,  it  assumes  a  more  brilliant  color, 
passing  through  violet  to  black,  but  on  cooling  regains  its 
original  tint.     It  is   readily  soluble  in   hot  hydrochloric 
acid  with  a  copious  evolution  of  chlorine.     In  nitric  acid 
it  is  only  partially  soluble,   lead   nitrate  and   insoluble 


214  THE   LEAD   AND   ZINC  PIGMENTS. 

lead  dioxide  being  formed  according  to  the  following 
equation : 

Pb304+4  HN03  =  2  Pb(N03)2  +  Pb02  +  2  H20. 

The  addition  of  a  little  alcohol  and  further  boiling  will, 
however,  effect  complete  conversion  into  lead  nitrate,  the 
alcohol  being  reduced  to  acetaldehyde. 

Pb02  +  2  HN03+C2H5OH  =  2  Pb(N03)2+CH3CHO  +  2  H20. 

298.  Adulteration.  Aside  from  purity,  red  lead  is  valued 
according  to  depth  and  brilliancy  of  tone,  the  production 
of  the  deepest  shades  being  considered  a  valuable  trade 
secret.     The  adulterating  of  red  lead  with  brick  dust  and 
oxide  of  iron  has  passed  into  disuse  and  when  sold  simply 
as  red  lead  it  will  usually  be  found  to  be  commercially 
pure.     There    are,    however,    numerous   combination    red 
leads  on  the  market  in  which  the  lead  has  been  brightened 
and  made  more  brilliant  by  the  use  of  an  organic  color, 
such  as  eosine,  precipitated  on  an  inert  base  like  barytes. 
These  combination  red  leads  are  usually  sold  slightly  below 
red  lead  prices,  and  while  they  serve  their  purpose  excel- 
lently, the  color  does  not  permanently  maintain  its  bril- 
liancy. 

299.  Selection  for  Vermilions.   Red   lead   which  is   in- 
tended to  be  ground  with  linseed  oil  and  placed  on  the 
market  in  sealed  packages  which  may  not  be  used  for  some 
months,  or  red  lead  which  is  to  be  used  in  the  manufacture 
of  vermilions,  should  be  selected  with  regard  to  litharge 
content,  as  there  is  great  danger  of  hardening  in  the  package, 
resulting  in  financial  loss  and  much  inconvenience.  A  simple, 
rapid  test  and  yet  sufficiently  accurate  test  for  the  purpose 
is  to  digest  2  grams  of  the  sample  in  50  c.c.  of  a  10  per 
cent  neutral  solution  of  lead  nitrate  on  the  water-bath  for 


THE  OXIDES  OF  LEAD.  215 

about  30  minutes.  The  free  litharge  will  be  taken  up  into 
solution,  and  the  undissolved  residue  collected  on  a  Gooch 
crucible,  washed,  dried  and  weighed.  A  red  lead  contain- 
ing 12  per  cent  of  soluble  oxide  is  not  suitable  for  the  above 
purposes.  The  limit  for  orange  mineral  may  be  taken  as 
6  to  8  per  cent  under  similar  treatment.  In  fact,  there 
are  only  one  or  two  grades  of  red  lead  in  this  country 
which  will  pass  these  requirements. 

300.  Red  lead  for  glassmaking  must  be  free  from  com- 
mercial impurities,  especially  copper  and  iron.     Red  lead 
for    match    making   is    valuable    in    proportion    to    the 
peroxide  it  contains,  which  may  vary  from  28  to  33  per 
cent. 

301.  Orange  Mineral.   This  product  may  be  considered 
as  a  debased  form  of  red  lead,  as  on  long  exposure  to  light 
it  darkens.     The  empirical  formula  of  orange  mineral  is 
the  same  or  closely  the  same  as  for  red  lead.     It  is  pre- 
pared  by  calcining  white  lead  or .  the  neutral  carbonate 
of   Lead.    The  finest  tints   arc  prepared  by  heating  the 
particles  of  white  lead  obtained  from  the  foam  from  the 
washing  and  settling  tanks  in  the  manufacture  of  white 
lead.     Much  of  the  orange  mineral  made  in  this  country 
is  prepared  by  calcining  the  more  or  less  basic  carbonate 
of  lead  obtained  by  dissolving  litharge  in  acetic  acid,  form- 
ing a  basic  acetate,  which  is  then  carbonated,  dried  and 
calcined  in  the  same  style  of  furnace  as  massicot,  at  a  care- 
fully regulated  temperature,  the  evolved  water  and  carbon 
dioxide  passing  up  to  the  flue.     Orange  mineral  is  less 
dense  than  red  lead,  having  a  specific  gravity  of  about 
6.95,  and  is  valued  according  to  the  depth  and  brilliancy  of 
its  bright  orange  shade. 


216  THE   LEAD   AND   ZINC  PIGMENTS. 

302.   Production  and  Imports  of  Red  Lead.1 


Production. 

Imports. 

Vpar 

Quantity. 

Value. 

Quantity. 

Value. 

Pounds. 

Pounds. 

1902 

23,338,252 

$1,263,112 

1,075,839 

$37,383 

1903 

17,664,000 

1,022,754 

1,152,715 

40,846 

1904 

18,340,731 

1,076,131 

836,077 

30,115 

1905 

32,756,000 

2,049,888 

704,402 

26,553 

1906 

27,616,000 

1,924,288 

1,093,639 

50,741 

1907 

40,156,000 

2,802,454 

679,171 

35,959 

303.    Production  and  Imports  of  Orange  Mineral.1 


Year. 

Production. 

Imports. 

Quantity. 

Value. 

Quantity. 

Value. 

1902 
1903 
1904 
1905 
1906 
1907 

Pounds. 
1,973,521 
1,302,000 

$139,349 
100,693 

Pounds. 
997,494 
756,742 
766,469 
628,003 
770,342 
615,015 

$49,060 
36,407 
37,178 
31,106 
42,519 
37,793 

1^  338,  000 

129^410 

Report,  Production  of  Mineral  Paints,  1902-1907. 


CHAPTER  XX. 

THE  LEAD   CHROMATES. 

304.  Varieties.   The    manufacture    of    chrome    yellows, 
orange  and  reds  has  increased  greatly  within  the  last  few 
years,  and  now  amounts  to  a  yearly  production  of  several 
thousand  tons.     Based  on  simple  chemical  principles  and 
requiring  a  comparatively  small  financial  outlay  for  equip- 
ment, their  manufacture  has  not  been  restricted  to  a  few 
firms  solely  engaged  in  the  color  business,  and  there  are  at 
the  present  time  at  least  a  dozen  of  the  larger  paint  houses 
who  prepare  their  own  chrome  pigments.     The  various 
shades  of  these  chrome  pigments  may  be  classified  accord- 
ing to  common  use  as  follows: 

Canary  yellow. 

Canary  yellow,  deep. 

Lemon  yellow. 

Chrome  yellow,  medium. 

Chrome  yellow,  orange. 

Chrome  yellow,  deep  orange. 

American  vermilion,  Chinese  scarlet,  etc. 

305.  Tinting    Strength.   Although    prepared    by    simple 
chemical   processes,   the   production   of   uniform   tints   of 
high  tinting  strength  is  by  no  means  an  easy  undertaking, 
as  a  careful  examination  of  the  chrome  colors  offered  to 
the  trade  will  show.     Exactness  of  method  and  careful 
attention  to  details  are  the  essential  elements  of  success. 
Two  chrome  yellows  may  appear  to  possess  identically  the 
same  tint  and  tone,  yet  when  reduced  with  equal  quan- 

217 


218  THE   LEAD   AND   ZINC   PIGMENTS. 

titles  of  a  white  pigment,  e.g.,  white  lead,  one  may  be  found 
to  possess  25  per  cent  more  strength  than  the  other  and  will 
still  maintain  a  clear  yellow  tone,  while  the  other  will  appear 
dirty  or  may  pass  over  into  another  tone  or  color  altogether. 
Chemically  these  yellows  may  be  the  same,  and  the  differ- 
ence is  therefore  due  to  the  methods  of  manipulation. 

306.  Presence    of   Lead   Sulphate.   The   lighter   colored 
chrome  yellows  contain  besides  neutral  lead  chromate  a 
varying  percentage  of  sulphate  of  lead,  the  function  of 
which  is  to  lighten  the  tint.     It  has  been  a  much  discussed 
question  as  to  whether  this  sulphate  of  lead  exists  free  or 
as  a  sulpho-chromate.     In  the  opinion  of  the  writer  the 
combination  is  very  similar  to  that  in  zinc-lead,  which  is 
very  closely  on  the  border  line  between  chemical  combi- 
nation and  mechanical  mixture,  due  to  the  exceedingly  close 
intimate  contact  of  the  component  particles,  and  the  rela- 
tions which  apply  under  these  circumstances  are  not  clearly 
understood. 

307.  Raw  Materials.   The  source  of  the  lead  in  the  manu- 
facture of  these  yellows  is  either  lead  nitrate  or  basic  lead 
acetate;   the   source   of   the   chromium   being   sodium   or 
potassium  dichromate  and  the  sulphate  radical  from  sul- 
phuric acid  or  sulphate  of  soda.     Lead  nitrate  produces  a 
much  richer,  clearer,  and  stronger  chrome  yellow  than  the 
acetate,  but  unfortunately  these  advantages  are  partially 
offset  by  the  higher  cost  of  the  lead  content  in  lead  nitrate 
than  of  the  lead  content  in  basic  lead  acetate,  and  most 
color   houses,  therefore,  prepare   their  yellows   from   the 
acetate,    which    they    make    themselves    from    ordinary 
litharge    or   from    color   makers'    oxide    and    commercial 
56  per  cent  acetic  acid.     While  it  is  possible  to  prepare 
on  a  commercial  scale  any  of  the  several  basic  acetates, 
the   one   most    commonly  used    corresponds   to    the  for- 
mula  Pb(C2H302)  .  PbO,   although    the    tribasic   acetate, 


THE  LEAD  CHROMATES.  219 

Pb(C2H302)2 .  2  PbO,  is  used  to  some  extent,  more  espe- 
cially in  the  deeper  yellows.  Each  is  prepared  by  first 
forming  the  neutral  acetate  and  then  digesting  with  the 
calculated  quantity  of  litharge  to  form  the  desired  acetate. 
The  litharge  used  for  this  purpose  should  be  selected  with 
regard  to  freedom  from  metallic  lead  and  red  lead,  both  of 
which  are  substantially  insoluble  in  the  acetic  acid  used 
and  would  therefore  affect  the  quality  of  the  color  product. 

308.  Sodium  Bichromate.     Either  the  sodium  or  potas- 
sium bichromate  may  be  substituted  for  the  other  in  chrome 
yellow  formulas  provided  the  quantities  required  are  cal- 
culated according  to  the  molecular  weights;  both  used 
with  the  same  lead  salt  will  produce  4the  same  tint  and 
strength.     Many  color  makers,  however,  prefer  to  use  the 
potassium  salt,  although  it  costs  about  a  cent  a  pound 
more,  because  it  does  not  attract  moisture  from  the  atmos- 
phere  on   standing   as   does   sodium   dichromate.      This 
absorption  of  moisture  decreases  the  apparent  chromium 
content  of  the  salt,  making  it  difficult  to  follow  the  work- 
ing formula  exactly.     A  number  of  color  houses  purchase 
their  sodium  dichromate  in  comparatively  tight  barrels 
and  prepare  a  large  quantity  of  stock  solution  at  a  time 
and  thus  avoid  the  above  difficulty, 

309.  Precautions  to  be  Observed.   Especial  precautions 
must  be  observed  in  the  preparation  of  the  lighter  colored 
yellows,  in  order  to  avoid  their  darkening  during  manu- 
facture.    These  precautions  may  be  summarized  as  fol- 
lows: 

1.  Use  of  very  dilute  solutions.- 

2.  Continuous  agitation  during  precipitation. 

3.  Maintenance  of    low  temperatures,  i.e.,   as    near 

room  temperature  as  possible. 

4.  Rapid  manipulation  during  the  precipitation  and 

especially  during  the  subsequent  washings. 


220  THE  LEAD  AND   ZINC  PIGMENTS. 

310.  Secret  Formulas.   Nearly  every   color  maker  has 
his  own  cherished   formulas  which  he  guards  with  the 
greatest  care.    In  the  majority  of  instances  his  efforts  in 
this  direction  are  needless,  as  the  essential  details  are  well 
understood  by  all  of  his  professional  brothers.     Among 
these  details  may  be  mentioned  the  advantage  of  using 
an  excess  of  about  five  per  cent  of  dichromate  above  what 
is  required  for  actual  combination,  the  tone  and  strength 
of  the  resulting  color  being  much  improved.     In  the  manu- 
facture of  lemon  yellows  it  is  customary  to  neutralize  the 
dichromate  with  the  calculated  quantity  of  sodium  car- 
bonate to  form  the^neutral  chromate  before  precipitating. 
In  order  to  obtain  the  light  clear  tone  required  of  a  canary 
yellow  a  small  quantity  of  tartaric  acid  is  added  to  the 
dichromate  solution.     A  yellow  obtained  by  this  method 
must  be  handled  with  care,  as  a  number  of  instances  are 
on  record  where  it  has  undergone  a  spontaneous  decom- 
position. 

311.  The  amount  of  sulphuric  acid  or  sulphate  of  soda 
used  will  depend  upon  the  lightness  or  paleness  of  the 
tint  desired.     However,   as  sulphate  of  lead  is  cheaper 
than  chromate  of  lead,  some  color  makers,  who  are  able 
to   produce   exceptionally   strong  yellows,   will  let   them 
down  with  sulphate  of  lead  until  of  only  average  strength, 
thereby  securing  an  increased  profit.     Twenty  to  thirty 
per  cent  will  represent  the  lead  sulphate  content  of  the 
usual  run  of  lemon  yellows.     Instead  of  using  a  soluble 
lead  salt  entirely,  it  may  be  partially  replaced  with  white 
lead,  a  portion  or  all  of  which  may  undergo  conversion 
into  chromate  or  sulphate  as  may  be  desired,  and  this 
affords  another  way  of  reducing  the  cost  of  a  chrome 
yellow,  although  at  the  expense  of  its  strength.     In  fact 
it  is  difficult,  if  not  impossible,  to  produce  as  strong  and 
clear  a  yellow  with  the  use  of  white  lead  as  without. 


THE   LEAD   CHROMATES. 


221 


312.  Practical  Formulas.  The  following  practical  work- 
ing formulas,  which  can  easily  be  adapted  to  tubs  of  any 
desired  size,  clearly  illustrate  the  points  above  discussed. 


Material. 

Lemon 
yellow. 

Canary 
yellow. 

Canary 
yellow, 
deep. 

Medium 
yellow. 

Lead  nitrate 

Ibs.     oz. 
100     00 

Ibs.     oz. 

Ibs.     oz. 
100     00 

Ibs.     oz. 

Litharge 

100     00 

100     00 

White  lead 

300     00 

Acetic  acid  (56%) 

43     12 

43     12 

Potassium  dichromate 

40     00 

Sodium  dichromate 

43     12 

60     00 

61       4 

Sulphuric  acid   

40     00 

Sodium  sulphate  (crystals) 

80     00 

Sodium  carbonate  (dry) 

17     10 

Xartaric  acid 

1     00 

313.  Precipitation.   The  amount  of  water  required  by 
these  formulas  depends  somewhat  upon  the  capacity  of  the 
tubs  and  the  output  required  of  the  color  maker.     It  is  of 
course  understood  that  the  chromium  solution  is  run  into 
the  lead  solution  always,  and  any  sulphate-forming  mate- 
rials or  modifying  materials  like  tartaric  acid  are  added  to 
the  chromate  solution   before  precipitation.      The  more 
closely  the  four  rules  above  referred  to  are  followed  the 
more  nearly  uniform  and  the  stronger  will  be  the  yellows 
produced. 

314.  Orange  Chrome  Yellows.     The  lighter  the  color  of 
the  yellow  produced,  the  more  amorphous  and  fluffy  it  is, 
and  in  passing  down  the  list  to  the  deeper  colors,  it  will  be 
noticed  that  they  become  more  and  more  crystalline  the 
more  orange  or  red  the  color,  the  deepest  colored  American 
vermilion    being    exceedingly    crystalline.     The    color    of 
these  compounds,  therefore,  depends  partly  on  the  physical 
structure,  but  more  especially  in  the  darker  chromes  upon 
the  formation  of  a  basic  lead  chromate,  which  instead  of 


222 


THE  LEAD  AND   ZINC  PIGMENTS. 


being  yellow  is  of  a  decidedly  red  color.  The  orange 
chromes  may  be  considered  as  mixtures  of  the  neutral 
chromate  and  basic  chromate.  They  are  prepared  by 
heating  the  chromate  after  formation  with  caustic  soda  or 
lime,  the  amount  of  lime  or  soda  and  the  length  of  heat- 
ing determining  the  color  produced.  The  following  work- 
ing formulas  will  serve  to  illustrate  the  manufacture  of  the 
medium  orange  and  deep  orange  shades. 


Materials. 

Orange. 

Deep  orange. 

Lead  nitrate  
White  lead..  
Sodium  dichromate 
Calcium  oxide  

Ibs.     oz. 
100     00 
80     00 
51     12 
10     00 

Ibs.     oz. 
100     00 
100     00 
75       8 
17     00 

315.  Addition  of  the  Calcium  Oxide.     The  calcium  oxide 
is  added  in  the  form  of  a  very  thin  paste  as  hydroxide, 
after   the   chromate   is  precipitated.     The  mass  is  then 
heated  until  the  desired  tint  is  produced,  more  lime  being 
added  if  necessary.    Although  lime  is  cheaper  than  caustic 
soda,  the  economy  of  its  use  is  somewhat  doubtful,  as  the 
reaction  with  caustic  soda  is  very  much  easier  to  control. 

316.  The  orange  chromes  will  not  darken  nearly  as  much 
during  the  washing  and  drying  processes  as  the  lighter 
yellows,  nevertheless  due  care  should  be  exercised  in  their 
preparation. 

317.  American  Vermilion.     This  pigment,  known  to  the 
trade  under  various  names  such  as  Chinese  scarlet,  Persian 
red,  etc.,  is  a  very  heavy,  strongly  crystalline  scarlet  red 
pigment.     Owing  to  the  fact  that  it  settles  very  rapidly 
when  mixed  with  oil  and  is  very  difficult  to  grind  owing  to 
its  becoming  very  much  lighter  in  color  due  to  the  crushing 
of  the  crystals,  together  with  its  comparatively  high  price, 


THE   LEAD  CHROMATES.  223 

it  has  quite  largely  passed  out  of  use,  although  as  a  rust 
resisting  pigment  for  iron  and  steel  painting  it  is  almost 
without  an  equal.  Its  proper  production  is  attended  with 
considerable  difficulty,  and  it  is  now  prepared  by  only  a  few 
firms,  who  have  practically  a  monopoly  of  the  business 
owing  to  the  fire  and  brilliancy  of  their  product. 

3 18.  White  lead  is  usually  the  lead  salt  used  in  the  pro- 
duction of  American  vermilion,  a  selected  grade  being  used 
for  this  purpose.     Some  authorities  consider  a  white  lead 
high  in  hydroxide  as  the  most  suitable,  but  according  to  the 
experience  of  the  author  the  physical  structure  of  the  white 
lead  is  the  more  important  consideration.     White  lead, 
composed  of  very  fine  particles,  as  Carter  or  Mild  process, 
will   not   yield    a   deep   American    vermilion,    whereas  a 
specially  prepared  lead,  containing  85  to  90  per  cent  car- 
bonate, and  which  has  a  coarse  crystalline  structure,  will 
yield  an  excellent  vermilion.     When  it  is  considered  that 
the  larger  the  crystals  the  deeper  the  tint,  this  view  is  the 
natural  one. 

319.  Preparation.    This  pigment  may  be  prepared  accord- 
ing to  several  methods.    The  following  formula,  however, 
with  careful  manipulation  will  give  excellent  results.     One 
hundred  pounds  of  white  lead  is  ground  into  a  very  thin, 
smooth  paste,  and  run  into  a  dilute  boiling  solution  of- 
potassium  dichromate,  28.5  pounds  in  60  gallons  of  water; 
the  dichromate  having  been  neutralized  with  crystallized 
sodium  carbonate,  about  27  pounds  being  required.     The 
boiling  is  continued  for  about  ten  minutes  or  until  the  pre- 
cipitate attains  the  desired  shade.     It  is  allowed  to  settle, 
the  supernatant  liquid  removed,  the   precipitate   washed 
and  then  treated  with  dilute  sulphuric  acid  (1  :  10),  an 
amount  equivalent  to  about  four  per  cent  of  the  weight  of 
the  chromate  produced  being  used.     The  mass  is  slowly 
stirred  until  the  desired  brilliancy  is  obtained.    The  acid  is 


224  THE   LEAD   AND   ZINC   PIGMENTS. 

then  immediately  neutralized  with  soda.  The  now  brilliant 
vermilion  is  washed  and  dried  in  a  vacuum  drier  or  on  a 
chalk  bed.  Some  manufacturers  use  caustic  soda  or  slaked 
lime  in  place  of  the  sulphuric  acid,  but  the  reaction  is  more 
difficult  to  control. 

320.  Care  in  Grinding.  Care  should  be  exercised  in  the 
drying  of  all  of  the  chrome  pigments,  as  temperatures 
above  60°  C.  are  liable  to  cause  alteration  of  shade.  The 
grinding  of  these  colors  also  requires  considerable  attention. 
The  lighter  colors  may  be  ground  in  a  fairly  tight  mill;  the 
medium  yellow,  if  from  acetate,  and  the  orange  shades  must 
be  ground  in  a  loose  mill,  while  the  vermilions  cannot  be  put 
through  a  grinding  process  at  all  without  destroying  their 
color. 


CHAPTER  XXI. 

LITHOPONE. 

321.  Early  History.     This  pigment,  the  best  grades  of 
which  contain  about  28.5  per  cent  zinc  sulphide,  1.5  per 
cent  zinc  oxide  and  70  per  cent  barium  sulphate,  has  been 
in  extensive  use  only  a  comparatively   few  years.     Its 
origin  dates  back  to  about  1874,  in  which  year  a  patent  was 
taken  out  by  a  J.  B.  Orr  in  England  for  the  manufacture  of 
a  zinc  sulphide  pigment  under  the  name  of  Orr's  White  or 
Orr's  White  Enamel.     Orr  prepared  his  'pigment  by  cal- 
cining an  intimate  mixture  of  barytes  and  charcoal  for 
several  hours  and  leaching  out  the  resulting  barium  sulphide 
with  water. 

322.  The  solution  obtained  was  divided  into  two  portions ; 
to  one  a  solution  of  zinc  chloride  was  added,  resulting  in  the 
formation  of   zinc   sulphate  and  barium  chloride.    With- 
out separating  the  precipitated  sulphide  of  zinc,  the  solu- 
tion was  then  treated  with  the  remaining  portion  of  barium 
sulphide,  and  a  sufficient  amount  of  zinc  sulphate  solution, 
the  combined  precipitates  washed,  filtered,  dried,  calcined, 
and  while  hot  thrown  into  cold  water,  which  made  the  pro- 
duct more  dense,  i.e.,  gave  it  greater  body.     This  was  fol- 
lowed, in  1875,  by  another  patent  by  Griffith,  who  made  use 
of  the  mixture  of  waste  sulphides,  calcium  and  sodium 
obtained  in  the  Leblanc  soda  process.     Since  that  date 
numerous  improvements  have  been  made  and  the  manu- 
facture of  zinc  sulphide  whites  has  been  successfully  intro- 
duced into  this  country,  the  product  being  sold  under  such 
fanciful  names  as  Lily  white,  Diamond  White,  Snow  White, 
Ponolith,  Beckton  White,  etc. 

225 


226  THE   LEAD   AND   ZINC  PIGMENTS. 

323.  Zinc  Sulphide.     Zinc  sulphide  itself  may  be  made 
by  adding  ammonium  sulphide  to  an  alkaline  solution  of 
any  zinc  salt,  giving  a  white,  slimy  precipitate  of  the  sul- 
phide of  zinc,  which,  however,  cannot  be  used  by  itself  as  a 
paint  pigment,  but  must  be  intimately  mixed  with  an  inert 
base  like  barytes.    According  to  Bell,  the  most  favored 
method  of  manufacture  at  the  present  time  is  quite  closely 
that  devised  by  Orr. 

324.  Preparation  of  Zinc  Sulphate.     The  zinc  sulphate 
is  prepared  in  several  ways.     In  Germany  it  is  prepared 
directly  from  ore;  in  the  United  States,  by  dissolving  metallic 
zinc  or  zinciferous  by-products  in  sulphuric  acid.     The 
practice  in  one  works  is  to  burn  the  zinc  out  of  scrap  brass, 
the  copper  being  left  behind  while  the  zinc  passes  as  a  white 
fume  (ZnO)  into  settling  chambers,  and  is  collected  and 
dissolved  in   sulphuric  acid,  the  solution  being  properly 
purified  before  being  used  for  lithopone. 

325.  Preparation  of  Barium  Sulphide.     The  barium  sul- 
phide is  usually  prepared  by  heating  an  intimate  mixture 
of  about  four  parts  crude  barytes  and  one  part  of  a  very 
low  ash  coal  in  a  revolving  furnace  for  two  to  three  hours  at 
a  bright  red  heat,  a  very  slight  amount  of  air  being  admitted. 
Sixty  to  seventy  per  cent  of  the  barytes  used  is  converted 
into  soluble  sulphide,  the  rest  remaining  as  insoluble  barium 
carbonate,  which,  after  being  entirely  freed  from  sulphide 
by  washing,  is  converted  into  barium  nitrate  or  barium 
chloride  as  desired. 

326.  Instead  of  coal  other  carbonaceous  materials  have 
been  proposed,  such  as  coal  tar,  which  is  incorporated  with 
the  barytes  in  a  chaser  before  being  charged  into  the  furnace. 
Potato  starch  has  also  been  used  and  one  to  two  per  cent  of 
the  weight  of  the  charge  of  calcium  chloride  added,  which 
gives  a  semi-paste  in  the  furnace. 

327.  Precipitating  and  Calcining.    The  calculated  quan- 


LITHOPONE.  227 

tity  of  barium  sulphide  is  added  in  the  precipitating  tub  to 
the  requisite  amount  of  zinc  sulphate  solution  when  an 
intimate  mixture  of  zinc  sulphide  and  barium  sulphate  is 
obtained  as  a  precipitate,  which  is  then  placed  in  a  rotary 
furnace  and  calcined  at  a  high  heat.  The  calcined  mass  is 
thrown  into  water,  ground  in  stone  mills,  washed  until  the 
wash  water  is  neutral,  settled,  filter  pressed  and  dried  on 
trays  in  drying  rooms  and  finally  powdered  by  running 
through  a  pulverizer. 

328.  Physical   Properties   of  Lithopone.1     The   body   of 
this  product  is  almost  equal  to  that  of  white  lead,  and 
Green  Seal  lithopone,  as  made  in  this  country,  is  equal 
to  that  of  French  process  zinc  white.     The  brands  sold  as 
Red  Seal,  Yellow  Seal,  Blue  Seal,  etc.,  are  simply  mixtures 
in   the  dry  way  of   Green   Seal   lithopone  and  ordinary 
barytes.     The  higher  the  calcination,  the  better  is  the  color 
and  the  less  oil  is  required  for  grinding  or  mixing  the  pig- 
ment and  the  better  it  will  work  under  the  brush.     When 
it  is  less  highly  calcined,  the  pigment,  while  favored  in  some 
industries,  is  unfit  for  the  use  of  the  painter,  because  it 
works  slimy  and  tends  to  thicken,  requiring  too  great  a 
quantity  of  thinners,  thereby  losing  body  or  opacity. 

329.  Reductions.     Comparing    the    percentage    of    oil 
required  for  100  pounds  of  white  paste  of  similar  con- 
sistency, we  may  place  the  figures  as  follows : 

Pure  white  lead 9J  per  cent. 

Green  Seal  lithopone 12    per  cent. 

American  zinc  oxide 14    per  cent. 

French  process  zinc 15    per  cent. 

330.  To    reduce    the  paste  so  ground   to    the    proper 
working   consistency    with    a    thinner    consisting    of    oil 

1  Oil,  Paint  and  Drug  Reporter,  LXXII,  No.  21,  page  38. 


228 


THE   LEAD   AND    ZINC  PIGMENTS. 


and  driers   would  require   for   100   pounds   paste   in   the 
case  of 

Pure  white  lead 4    gallons. 

Green  Seal  lithopone 64  gallons. 

American  zinc  oxide ,. . .  8    gallons. 

French  process  zinc 8J  gallons. 

331.   The  relative  percentages  of  dry  pigment  and  vehicle 
in  the  paints  so  prepared  would  then  figure  out  as  follows : 


'.* 

Pigment. 

Liquid. 

Per  cent. 

Per  cent. 

Pure  white  lead  paint  

71.28 

28.72 

Gre.en  Seal  lithopone  paint  .  .  . 

58.50 

41.50 

American  zinc  white  paint  .  .  . 

53.10 

46.90 

French  process  zinc  paint.  .  .  . 

51.30 

48.70 

332.  Comparison  with  White  Lead.     The  chief  points  in 
favor  of  lithopone  as  compared  with  white  lead  and  zinc 
white  are  the  greater  opacity  and  greater  elasticity  as  com- 
pared with  zinc  oxide,  and  its  inertness  in  the  presence  of 
sulphur  gases  which  tend  to  discolor  white  lead  paint.     On 
the  other  hand  lithopone  has  one  drawback,  that  of  black- 
ening when  exposed  to  the  sun  before  it  has  become  thor- 
oughly dry.    Also  when  mixed  with  white  lead  or  colors 
containing  a  copper  or  lead  base,  it  will  blacken,  due  to  the 
formation  of  sulphide  of  lead.     This  is  also  liable  to  happen 
when  a  drier  containing  lead  salts  is  used  in  the  oil  paint. 

333.  Grades  of  Lithopone.     As  before  stated  lithopone  is 
graded  according  to  its  zinc  sulphide  content,  other  con- 
siderations  being   equal.     In   Germany   four   grades    are 
usually  offered :  Green  Seal,  which  consists  of  approximately 
one  part  zinc  sulphide  to  two  parts  barium  sulphate;  Red 
Seal,  consisting  of  one  part  of  zinc  sulphide  to  three  parts 


LITHOPONE. 


229 


barium  sulphate;  Blue  Seal,  one  part  of  zinc  sulphide  and 
four  parts  barium  sulphate;  and  Yellow  Seal,  one  part  zinc 
sulphide  and  five  parts  barytes.  It  is  asserted  by  some 
German  authorities  that  the  addition  of  ten  to  fifteen  per 
cent  of  calcium  carbonate  in  the  grinding  of  lithopone  in 
linseed  oil  reduces  the  liability  of  the  lithopone  to  blacken 
on  exposure  to  light.  In  this  country,  also,  several  patents 
have  been  granted  for  improvements  in  preventing  darken- 
ing. As  lithopone  is  largely  used  in  the  manufacture  of 
enamels  for  furniture,  bedsteads,  etc.,  permanency  of  color 
and  density  of  product  as  well  as  original  whiteness  are 
prime  considerations. 

334.  Manufacturers.  As  far  as  the  writer  has  been  able 
to  ascertain  the  following  list  represents  the  manufacturers 
in  this  country. 


No. 

Company. 

Location. 

1 

Beckton  Chemical  Company 

Beckton   N    J 

2 

Cawley  Clark  &  Co 

Newark   N    J 

3 

Cheeseman  Chemical  Company  

Scranton,  Pa. 

4 
5 

Excelsior  Manufacturing  Company  .  . 
Grasselli  Chemical  Company 

Newport,  Del. 
Grasselli   N   J 

6 

Harrison  Bros    &  Co 

Philadelphia   Pa 

7 

Heller  &  Mertz 

New  York 

8 
9 

Krebs  Pigment  &  Chemical  Company 
New  Jersey  Zinc  Company 

Newport,  Del. 
Palmerton   Pa 

10 

N.  Z.  Graves  &  Co  

Philadelphia  Pa. 

335.  Production.  The  production  of  lithopone  is  increas- 
ing rapidly  in  this  country,  indicating  that  consumption 
is  increasing  steadily,  as  in  1906,  4,300  tons,  valued  at 
$311,500,  were  manufactured  as  against  10,275  tons,  valued 
at  $750,350  in  1907. 


CHAPTER  XXII. 

PHYSICAL  PROPERTIES  OF  WHITE  LEAD. 

336.  Amorphous  Character  of  White  Lead.     Chemical 
analysis  cannot  be  relied  upon  entirely  for  information 
regarding  the  amorphous  character  of  white  lead,  and  it  is 
a  mistake  to  assume  that  because  the  ratio  of   carbonate 
to  hydroxide  found   agrees  closely  with  the  theoretical 
the  sample  in  question  is   always  a  desirable   product, 
for  it  is  by  no  means  rare  to  find  crystalline  carbonates 
present  in  quantity  when  a  chemical  analysis  will  show 
less  than  the  theoretical  amount  of  carbonate.    A  close 
examination  with  the  microscope  and  a  close  comparison, 
microscopically,  with  the  accepted  standards  should  always 
be  made,  and  the  results  of  such  examination  should  be 
considered  of  equal  value  to  the  data  obtained  chemically. 

337.  Color.     The  color  or  whiteness  of  white  lead  can 
only  be  judged  by  comparison  with  an  accepted  standard 
kept    for  that   purpose.     The  two  leads,    standard  and 
sample,  are  weighed  out  in  gram  lots  on  to  a  large  glass 
plate,  twelve  drops  of  bleached  linseed  oil  added  to  each 
and  rubbed  up  thoroughly  and  matched  up  on  a  micro- 
scope slide,  the  leads  being  spread  out  evenly.    The  color 
should  be  judged  from  both  sides  of  the  glass.    After 
comparing  the  color,  place  the  slide  in  the  steam  oven 
for  two  hours.     This  will  give  some  idea  as  to  the  amount 
of  yellowing  that  will  occur  when  the  lead  is  used  in  paint- 
ing.   This  defect  is  particularly  marked  in  pulp  leads. 

338.  Cautions  to  be  Observed.   If  the  particles  of  one  of 
the  leads  are  much  finer  than  those  of  the  other,  the  above 

230 


PHYSICAL  PROPERTIES  OF  WHITE  LEAD.  231 

test  may  appear  deceptive,  as  the  surface  of  the  former 
will  have  a  considerable  luster,  due  to  the  smoothness  of 
the  surface  and  its  apparent  oiliness.  This  condition  may 
be  observed  at  once  if  the  slide  be  held  in  different  posi- 
tions with  regard  to  the  source  of  light,  and  the  sample 
under  examination  can  often  be  made  to  appear  darker 
or  lighter  than  the  standard  at  the  will  of  the  operator. 
In  order  to  get  a  true  comparison  under  such  conditions, 
a  small  amount  of  each  lead  should  be  placed  side  by  side 
on  the  edge  of  a  piece  of  cardboard  or  blotting  paper  and 
then  flattened  out  uniformly  with  one  motion  of  a  palette 
knife.  The  cardboard  or  blotter  will  after  a  short  time 
have  absorbed  sufficient  oil  to  render  the  comparison  of 
the  whiteness  of  the  two  surfaces  fair. 

339.  Opacity.     Two    grams    each    of  the   sample    and 
standard  are  very  carefully  rubbed  up  with  0.01   gram  of 
a  high  grade  of  ultramarine  blue  and  twenty-four  drops  of 
bleached  oil.     This  operation  should  be  conducted  on  a 
large  sheet  of  glass,  using  a  flat-bottomed  glass  pestle  or 
muller.     A  uniform   pressure   and   the  same   number   of 
grinding  motions  should  be  used  with  regard  to  sample 
and  standard.     After  a  certain  number  of  motions   the 
material  should  be  gathered  up  with  a  sharp -edged  spat- 
ula and  again   ground  out,  until  the  operator  is   satisfied 
both  leads  have  been  treated  exactly  alike.     Instead  of  a 
glass  muller  a  palette  knife  may  be  used  if  sufficient  care 
is  observed. 

340.  The  more  strongly  the  lead  is  colored,  the  weaker 
it  is  in  hiding  power  or  opacity.    Adding  weighed  amounts 
of  lead  until  the  colors  are  of  equal  depth  will  show  the 
ratio  between  the  two.     Some  leads  are  so  crystalline  that 
a  great  difference  in  opacity  is  observable. 

341.  Oil  Requirements  and  Reductions.     "Fhe  amount  of 
oil  required  in  grinding  white  lead  can  only  be  determined 


232  THE   LEAD   AND   ZINC  PIGMENTS. 

by  experiment,  preferably  in  a  mill  of  the  regular  size. 
In  determining  the  reduction  which  the  various  white 
leads  and  pastes  will  stand,  some  convenient  method 
should  be  adopted  for  calculating  the  amount  of  oil  used 
in  gallons  per  hundred  pounds  of  paste.  One  of  the 
simplest  schemes  is  to  weigh  out  the  leads  or  pastes  in 
12J  ounce  quantities  or  multiples  thereof.  Then  each 
ounce  of  oil  used  is  equivalent  to  one  gallon  per  hundred 
pounds  of  paste. 

One  gallon  is  equivalent  to  128  ounces. 

One  hundred  pounds  are  equivalent  to  1600  ounces. 

1600  -  128  -  12.5. 

If  larger  amounts  were  required,  the  necessary  multiple 
of  12J  should  be  used  and  the  other  figures  increased 
accordingly. 

342.  In  this  way  the  necessary  quantities  of  turpen- 
tine and  drier  can  be  readily  calculated  and  measured  out. 
For  instance,  if  a  specification  to  be  tested  out  read, 

100  pounds  white  lead, 
7  gallons  raw  linseed  oil, 
^  gallon  turpentine, 
J  gallon  turpentine  drier, 

the  above  scheme  would  call  for 

12 J  ounces  white  lead, 
7  ounces  raw  linseed  oil, 
J  ounce  turpentine, 
|  ounce  turpentine  drier. 

343.  Laboratory  Tests  for  Opacity  and  Covering  Power. 
It  is  oftentimes  desirable  to  conduct  small  laboratory  tests 
for  opacity  and  spreading.    A  very  convenient  method  is 
to  lay  off  equal  squares  on  a  stiff  cardboard  one  side  of 
which  has  been  painted  black;    then  with  standard  and 


PHYSICAL  PROPERTIES  OF  WHITE   LEAD.  233 

sample  reduced  alike,  apply  equal  amounts,  and  brush 
out  evenly  with  a  carefully  selected  brush.  The  cards 
should  be  allowed  to  dry  in  a  place  free  from  laboratory 
fumes  or  gases  and  should  be  exposed  to  as  strong  a  light 
as  possible.  It  should  be  remembered  that  in  subdued 
light,  or  if  the  cards  are  allowed  to  remain  on  top  of  each 
other  after  drying,  the  tests  will  rapidly  turn  yellow,  due  to 
the  yellowing  of  the  linseed  oil.  This  fact  should  always 
be  taken  into  consideration  when  judging  the  whiteness. 
If  the  standard  and  sample  will  not  stand  the  same  reduc- 
tions the  above  scheme  will  apply  equally  well  in  judging 
body  obtained  and  amounts  used. 

344.  Microscopical  Measurements.     The  actual  determi- 
nation of  the  size  of  the  individual  particles  of  white  lead 
is  a  difficult  task,  as  they  tend  to  agglomerate  together, 
rendering  them  apparently  larger  than  they  really  are. 
However,  this  danger  may  be  avoided  by  taking  a  small 
quantity  of  the  lead  and  working  it  out  very  carefully  with 
a  drop  of  linseed  oil  on  a  microscope  slide  until  thorough 
incorporation  is  secured,  then  gradually  incorporating  one 
or  two  drops  of  petroleum  spirits,  such  as  is  commonly 
used  as  a  substitute  for  turpentine,  until  the  particles  are 
spread  over  a    sufficient   area   for  suitable  examination 
under  the  microscope. 

345.  Determination   of   the    Specific   Gravity.    Formerly 
the  determination  of  the  specific  gravity  of  a  pigment 
was  deemed  very  useful  in  calculating  the  exact  volume 
which  a  specified  weight  of  pigment  and  oil  would  occupy. 
But  actual  demonstration  has  proven  that  this  is  not  the 
case.     The  "  bulking  "  figure  of  a  pigment  in  oil  depends 
much   on   its  physical  structure  and  the  method  of  in- 
corporation with  the   oil.      For  a   great  many  purposes 
however,  the  knowledge  of  the  specific  gravity  is  very 
desirable. 


234  THE  LEAD  AND   ZINC   PIGMENTS. 

346.  The  determination  is  best  accomplished  by  the  use 
of  the  pycnometer  or  specific  gravity  bottle;  the  25-c.c. 
size  provided  with  thermometer  is  the  most  suitable.     The 
weight  of  the  pycnometer,  thoroughly  cleaned  and  dried, 
is  determined.     The  pycnometer  is  then  filled  with  pure 
distilled  water  at  a  temperature  which  has  been  definitely 
decided  upon;  15.5°  C.   (60°  F.)  or  22°  C.   (average  room 
temperature)    are    the    most    usual    temperatures.     The 
pycnometer  with  contents  is  then  weighed  and  the  weight 
of  the  water  obtained  by  subtraction.     The  pycnometer 
is  then  emptied,  thoroughly  dried,  cooled  and  filled  with 
turpentine;  flask  and  contents  must  be  of  the  same  tem- 
perature as  in  preceding  case.     The  weight  of  the  turpen- 
tine is  obtained,  and  this  weight,  divided  by  the  weight  of 
the  water,  gives  the  specific  gravity  of  the  turpentine  at 
that  temperature. 

347.  The  pycnometer  is  then  emptied,  the  inside  of  the 
neck  wiped  dry,  a  small  cone  of  paper  inserted  and  a  care- 
fully weighed  amount  of  pigment,  5  to  10  grams,  intro- 
duced without  loss  into  the  pycnometer,  which  is  then 
about  two-thirds  filled  with  some  of  the  same  turpentine 
above  referred  to.     By  careful  agitation  and  the  use  of  a 
platinum  wire,  all  of  the  air  bubbles  that  may  be  present 
in  the  pigment  are  eliminated,  the  cap  and  thermometer 
placed  in  position  and  the  flask  allowed  to  stand  fifteen 
minutes  to  half  an  hour  in  order  to  secure  proper  pene- 
tration into  the  pigment  particles.     The  pycnometer  is 
then  filled  with  the   turpentine,   brought   to   the  proper 
temperature  and  weighed,  and  the  specific  gravity  of  the 
pigment  determined  as  by  the  following  example : 

Weight  of  pycnometer 24 .8065  grams 

Weight  of  water  at  22°  C 25. 1100  grams 

Weight  of  turpentine  at  22°  C. . .  .  21 .7202  grams 


PHYSICAL  PROPERTIES   OF  WHITE  LEAD.  235 

21.7202  -s-  25.1100  =  0.8650,  specific  gravity  of  turpen- 
tine at  22°  C. 

Weight  of  pigment  taken 10 . 0  grams 

.Weight  of  pigment  (plus  above 

weight  of  turpentine) 31 . 7202  grams 

Weight  of  pigment  and  turpentine 

together  in  flask 30.4135  grams 

Weight  of  turpentine  occupied  by 

10  grams  of  pigment 1 . 3067  grams 

10.0  -5-  1.3067  =  7.653,  specific  gravity  of  pigment  as 
compared  with  turpentine. 

7.653  X  0.865  =  6.62  (approximate),  specific  gravity 
of  pigment  as  compared  with  water,  the  accepted  standard. 

348.  Turpentine,  owing  to  its  mobile  nature,  is  prefer- 
able to  water  as  a  medium  determining  specific  gravities  of 
pigments,  especially  as  some  white  leads  contain  traces 
of  oil. 

349.  Displacement  in  Oil.  The  volume  that  a  pigment 
will  occupy  in  linseed  oil  or  other  vehicles  is  dependent  to 
certain  degree  on  the  nature  of  the  vehicle,  the  physical 
structure  of  the  pigment  and  the  method  of  incorporation. 
For  instance  a  mixture  of  white  lead  and  zinc  oxide  incor- 
porated  with  linseed   oil   in  an  ordinary  mixer  and   run 
through  a  mill  will  occupy  an  altogether  different  volume 
than  if  the  mixture  was  thoroughly  chased  under  heavy 
pressure  before  grinding.     Likewise  the  determination  of 
the  "  bulking  "  figure,  so-called,  of  a  pigment  in  linseed  oil 
will  be  much  different  if  determined  by  simple  displace- 
ment accompanied  by  suitable  agitation,  than   when  the 
pigment  is  thoroughly  ground  with  the  oil,  under  consider- 
able pressure.     The  following  table,  prepared  by  the  author, 
clearly  shows  this  difference. 


236 


THE   LEAD   AND   ZINC  PIGMENTS. 


350.  "  Bulking "  Figure  or  the  Number  of  Pounds 
required  to  displace  One  Gallon  (231  Cubic  Inches)  of 
various  Lead  and  Zinc  Pigments. 


No. 

Name  of  pigment. 

Simple, 
displace- 

Grinding 
in  linseed 

Displace- 
ment  in 

ment   in 

oil 

turpen- 

linseed oil. 

tine. 

Lbs. 

Lbs. 

Lbs. 

1 

Dutch  process  white  lead  

67.30 

55.86 

80 

2 

Carter  white  lead  

55.90 

3 

Mild  process  white  lead  

54.74 

45.90 

78.88 

4 

Matheson  white  lead 

33  90 

5 

Sublimed  white  lead 

43  85 

51   60 

63  80 

6 

Zinc  lead  white 

49  00 

49  81 

48  70 

7 

Zinc  oxide 

55  30 

47  14 

44  90 

8 

Lithopone        .                .    . 

38  30 

35  29 

34  60 

9 

Chrome  yellow,  light  

60.66 

50.57 

11.40 

10 

Chrome  yellow,  medium  

45.24 

44.22 

10.70 

351.  The  Determination.  The  displacement  figures  in 
raw  linseed  oil  were  obtained  by  weighing  the  pigment 
into  a  pycnometer,  about  one-half  full  of  oil,  incorporating 
as  thoroughly  as  possible  with  a  platinum  wire,  placing 
on  top  of  steam  oven  for  several  hours  in  order  to  secure 
better  penetration  in  and  among  the  pigment  particles, 
and  finally  cooling,  making  to  volume  and  weighing  in 
the  usual  manner.  The  "  bulking "  figures  obtained  by 
grinding  were  secured  by  taking  from  100  grams  in  the  case 
of  heavy  pigments,  to  25  grams  for  the  lightest  pigments 
and  grinding  thoroughly  with  sufficient  oil  to  make  a  thin 
smooth  paste,  in  a  glass  mortar,  using  considerable  pres- 
sure and  the  greatest  possible  care  to  obtain  an  even  grind, 
finally  transferring  with  the  aid  of  a  sharp  spatula  to  a 
100-c.c.  pycnometer,  removing  the  last  portions  from  the 
mortar  with  more  oil,  allowing  to  stand  on  top  of  the  steam 
oven  for  several  hours  for  removal  of  all  air  bubbles,  cool- 
ing, making  to  volume  and  weighing.  For  ease  in  com- 


PHYSICAL  PROPERTIES   OF  WHITE  LEAD.          237 

mercial  calculations  7|  pounds  of  raw  linseed  oil  and  7 
pounds  of  turpentine  were  considered  as  equivalent  to 
1  gallon.  A  small-necked  100-c.c.  Erlenmeyer  flask,  cali- 
brated by  the  author,  was  used  by  him  for  the  pycnometer, 
as  its  shape  was  more  convenient  for  the  purpose  than  the 
ordinary  type  of  pycnometer. 


CHAPTER  XXIII. 

PRACTICAL  TESTS. 

352.  The  North  Dakota  Paint  Tests.    In  1907,  the  North 
Dakota  Experiment  Station,  under  the  direction  of  E.  F. 
Ladd  and  the  author,  undertook  an  extensive  series  of 
practical  paint  tests  covering  a  large  number  of  mixed 
paint  formulas  and  a  number  of  the  leading  brands  of 
white  leads  and  zinc  pigments.     These  tests  were  placed 
on  the  test  fences  illustrated  in  this  connection,  a  descrip- 
tion of  which  may  be  found  in  the  chapter  on  Practical 
Testing  Out  of  Paints  in  the  author's  work  on  Analysis  of 
Mixed   Paints,   Color  Pigments   and   Varnishes.     The   re- 
ductions and  applications  of  these  paints  were  conducted 
with  extreme  care  and  the  following  figures  with  regard 
to  the  reductions  employed  and  areas  covered,  as  calcu- 
lated  from   Bull.   No.   81,   and   the   Experiment   Station 
records  may  be  of  interest. 

353.  Reductions.   Early  in  1908,  the  editor  of  one  of  the 
leading  paint  magazines  sent  out  an  extensive  inquiry  to 
the  painters  throughout  the  country  regarding  the  reduc- 
tions which  they  advised  with  white  lead,  on  both  old  and 
new  work  and  on  various  kinds  of  wood.     The  author 
had  the  opportunity  of  examining  the  replies  received, 
which  were  numerous,  and  he  was  much  impressed  with 
the  lack  of  agreement.     In  fact  it  was  difficult  if  not  im- 
possible to  formulate  from  them    any  general    rules    or 
principles. 

The  reductions  used  on  the  North  Dakota  tests  for  the 
lead  and  zinc  pigments  were  arrived  at  after  numerous 

238 


PRACTICAL  TESTS. 


239 


240 


THE  LEAD  AND   ZINC  PIGMENTS. 


joint  experiments  by  Mr.  J.  B.  Campbell,  the  well-known 
paint  expert,  Mr.  Nelson,  a  painter  of  wide  experience,  and 
the  author,  and  as  the  materials  applied  have  shown  very 
high  service  values,  having  been  exposed  for  upwards  of 
two  years,  without  much  apparent  deterioration,  these 
reductions  may  be  regarded  as  very  satisfactory.  It  is  to 
be  noted  f  that  the  work  was  three  coat  over  the  kinds  of 
wood  indicated,  the  time  of  application  being  the  middle 
portion  of  the  summer. 

354.   Red  Seal,  White  Lead,  Eagle  White  Lead,  Carter 
White  Lead  and  Sublimed  White  Lead.1 


First  coat. 

Second  coat. 

Third  coat. 

White  lead  

100  Ibs. 

100  Ibs. 

100  Ibs 

Raw  linseed  oil  

5^  gal. 

3    gal. 

3  gal. 

Turpentine 

\  eal 

\  sal 

Drier  .... 

i  ffal 

355.    Matheson  White  Lead.1 


First  coat. 

Second  coat. 

Third  coat. 

White  lead     

100  Ibs. 

100  Ibs. 

100  Ibs. 

Raw  linseed  oil 

8    eal 

4  eal 

4    gal 

Turpentine 

i  eal 

1  ffal 

±  eal 

356.    Zinc-Lead  White. 


First  coat. 

Second  coat. 

Third  coat. 

Zinc  lead                              •    • 

100  Ibs 

100  Ibs. 

100  Ibs 

Raw  linseed  oil                   .    . 

5i  eal 

4    gal. 

3  gal 

Turpentine 

i  gal 

4  eal. 

Drier 

7  £<"• 

i  gal 

Bulletin  No.  81,  North  Dakota  Experiment  Station. 


PRACTICAL  TESTS. 
357.   Mild  Process  White  Lead. 


241 


First  coat. 

Second  coat. 

Third  coat. 

No.  1.     Double  chased 
White  lead            

100  Ibs. 

100  Ibs. 

100  Ibs. 

Raw  linseed  oil  

6    gal. 

4  gal. 

3i  gal. 

Turpentine  

i  gal. 

1  gal. 

4  gal. 

Drier                  

A  gal. 

No.  2.    Mixed  and  ground 
White  lead            

100  Ibs. 

100  Ibs. 

100  Ibs. 

Raw  linseed  oil          

6   gal. 

4    gal. 

31  gal. 

Turpentine               

i  gal. 

f  gal. 

i  gal. 

Drier 

A  cal 

NOTE  . —  No.  1  was  double  chased  only,  beinsj  allowed  t->  sweat  f  :r  24  hours  between 
chasings;  92  pounds  lead,  8  pounds  ril;  c  nsi  ten-y  medi--m  soft.  No.  2  same  pro- 
portions of  lead  and  oil,  but  put  through  ordinary  mixer  and  ground  in  30-inch 
mill ;  consistency  stiff. 


358.   New  Jersey  Zinc  Oxide  "  XX.' 


First  coat. 

Second  coat. 

Third  coat. 

Zinc  oxide  

100  Ibs. 

100  Ibs. 

100  Ibs 

Raw  linseed  oil  

10    gal. 

5*  gal. 

6  eral 

Turpentine  

i  gal. 

1    gal. 

Drier 

i  eal 

359.  Covering  Tests.  Each  of  these  paints  was  applied 
over  hard  pine  boards,  soft  pine  boards,  cedar  clapboard 
siding,  and  white  pine  clapboard  siding,  the  surface  cov- 
ered being  approximately  six  and  one-half  square  feet 
with  each  wood.  The  weights  of  paint  applied  were  care- 
fully determined  and  the  following  tables  of  figures  were 
obtained  by  calculating  back  to  the  paste  form,  i.e.,  the 
form  in  which  the  goods  were  received  in  the  original 
package,  and  in  the  case  of  white  leads  this  represented 
the  packages  as  found  on  the  market.  These  calculations 

1  Bulletin  No.  81,  North  Dakota  Experiment  Station. 


242 


THE   LEAD   AND   ZINC  PIGMENTS. 


PRACTICAL  TESTS. 


243 


were  prepared  from  the  tables  in  Bulletin  81,  North  Dakota 
Experiment  Station,  and  the  author  believes  them  to  be 
measurably  accurate.  The  Mild  process  tests  were  made 
at  a  later  date,  Mr.  Campbell  not  being  present.  The  con- 
ditions, however,  were  entirely  similar,  and  the  figures  are 
from  the  official  figures  recorded  at  that  time.  The 
results  are  calculated  in  grams  per  100  square  feet.  Not 
enough  Matheson  white  lead  was  available  for  full  sized 
tests  and  the  amounts  applied  were  not  noted. 

360.   Hard  Pine  Boards,  100  Square  Feet. 


First  coat. 

Second 
coat. 

Third  coat. 

Total. 

Red  seal    

Grams. 
1330 

Grams. 
863 

Grams. 
725 

Grams. 
2918 

Eagle 

1182 

678 

714 

2574 

Carter  

1221 

677 

559 

2457 

Sublimed  

1131 

672 

635 

2438 

Mild   process  No.  1  (double 
chased)  
Mild  process  No.  2   (mixed 
and  ground)  

1295 
1146 

661 
688 

603 

668 

2459 
2502 

Zinc-lead  white  
Zinc  oxide  

1105 
702 

432 
531 

555 
432 

2092 
1665 

361.   Soft  Pine  Boards,   100  Square  Feet. 


First  coat. 

Second 
coat. 

Third  coat. 

Total. 

Red  seal  

Grams. 

884 

Grams. 
731 

Grams. 
757 

Grams. 
2372 

Eagle  

1084 

610 

573 

2267 

Carter  

1038 

645 

767 

2450 

Sublimed 

975 

676 

654 

2305 

Mild  process  No.  1  (double 
chased)  

931 

598 

520 

2049 

Mild  process  No.  2  (mixed 
and  ground)  

918 

621 

619 

2158 

Zinc-lead  white  

1027 

595 

601 

2223 

Zinc  oxide  

662 

474 

391 

1527 

244  THE   LEAD   AND   ZINC  PIGMENTS. 

362.    Cedar  Clapboards,   100  Square  Feet. 


First  coat. 

Second 
coat. 

Third  coat. 

Total. 

Red  seal 

Grams. 
1361 

Grams. 
974 

Grams. 
815 

Grams. 
3150 

Eagle 

1472 

1027 

808 

3307 

Carter        

1152 

777 

750 

2679 

Sublimed  

1208 

852 

644 

2704 

Mild  process  No.  1   (double 
chased)  

907 

547 

548 

2002 

Mild  process  No.  2   (mixed 
and  ground)  
Zinc-lead  white  

1005 
1185 

601 

432 

636 
538 

2242 
2155 

Zinc  oxide  

924 

481 

462 

1867 

363.    White  Pine  Clapboards,  100  Square  Feet. 


First  coat. 

Second 
coat. 

Third  coat. 

Total. 

Red  seal                          • 

Grams. 
1288 

Grams. 
594 

Grams. 
577 

Grams. 
2459 

Bade 

1215 

933 

639 

2787 

Carter 

1191 

1045 

719 

2955 

Sublimed 

1275 

750 

704 

2729 

Mild  process  No.  1  (double 
chased)                     

1301 

763 

782 

2846 

Mild  process  No.  2  (mixed 
and  ground)             

1265 

752 

796 

2813 

Zinc-lead  white        

1168 

641 

449 

2258 

Zinc  oxide        

794 

547 

480 

1811 

364.  Conclusion.  In  the  opinion  of  those  who  con- 
ducted the  tests  there  was  no  choice  in  the  hiding  power 
of  any  of  the  white  leads  after  the  third  coat  had  been 
applied  and  dry  enough  to  warrant  inspection.  The  author 
leaves  all  conclusions  to  the  reader,  who  if  he  may  care  to 
do  so  can  easily  calculate  the  area  covered  per  100  pounds, 
which  is  the  more  usual  form  of  expression,  or  similarly 
calculate  the  total  area  covered  per  100  pounds  irre- 
spective of  the  varieties  of  wood  over  which  applied.  It 


PRACTICAL  TESTS.  245 

is  not  the  purpose  of  the  author  to  advertise  any  particular 
brand  or  process,  and  the  above  figures  are  here  given  to 
show  the  variations  in  amounts  applied,  even  with  an 
exceedingly  experienced  and  careful  brush  hand  and  under 
as  like  conditions  as  possible,  and  to  act  as  a  suggestion 
that  it  is  unwise  to  state  definite  empirical  figures  from  a 
single  test. 


CHAPTER  XXIV. 

THE  ART  OF  GRINDING  WHITE  LEAD,  PASTES,  AND  PAINTS. 

365.  Importance    of    Careful  Grinding.     This    is    essen- 
tially  an  age  of  competition,   a  fact  which  has  become 
especially  noticeable  in  the  paint  industry.     Paint  manu- 
facturers have  been  accustomed  to  large  profits,  which  are, 
however,  rapidly  becoming  a  thing  of  the  past,  and  the 
manufacturer  must  accustom  himself  to  a  moderate  return 
on  his  invested  capital,  and  pay  closer  attention  to  the 
details  of  his  business.     The  grinding  of  cheap  combina- 
tion white  leads  and  selling  them  as  pure  white  leads  is 
not  the  profitable  business  it  was  formerly;   the  consum- 
ing public  is  getting  wiser  and  more  discriminating.     Manu- 
facturers whose  specialty  is  cheap  "  dope  "  paints,  or  who 
in  order  to  retain  the  odor  of  sanctity  manufacture  and 
sell  them  through  a  subsidiary  corporation  or  company, 
are   finding  it   harder  and  harder  with  each  succeeding 
year  to  dispose  of  their  wares.     This  means  that  paint 
manufacturers  in  order  to  hold  their  trade  will  have  to 
use  better  materials.     Many  manufacturers  have  come  to 
realize  this  and  are  so  doing.     Good  materials,  however, 
do  not  make  good  paint  unless  these  materials  are  prop- 
erly ground  and  incorporated.     This  requires  time  in  the 
mixing  and  grinding,  which  involves  a  considerable  item 
of  expense  in  keeping  the  mills  properly  dressed. 

366.  Careless  Grinding.    Many  manufacturers  are  very 
slow  to  recognize  the  importance  of  careful  and  fine  grind- 
ing.    The  writer  while  a  member  of  the  staff  of  the  North 
Dakota  Experiment  Station  examined  54  paints  consist- 

246 


GRINDING   WHITE   LEAD,  PASTES,   AND   PAINTS.      247 

ing  of  whites,  colonial  yellows,  and  grays  which  were  sup- 
posed to  have  been  prepared  with  especial  care  by  the 
manufacturers,  as  they  were  used  to  demonstrate  the 
wearing  values  of  various  pigments  and  formulas.  After 
having  stood  under  average  conditions  for  8  months  they 
were  examined  in  the  can  as  to  condition.  Twelve,  or 
22  per  cent,  were  coarse,  giving  evidence  of  very  careless 
grinding;  15,  or  28  per  cent,  gave  evidence  of  hardening, 
also  presumably  due  to  lack  of  care  in  preparation  or  of 
observing  suitable  precautions  in  grinding.  Fifty  per  cent 
only  were  in  first- class  condition.  Yet  these  54  paints 
came  from  the  largest  and  most  progressive  houses,  whose 
aggregate  yearly  sales  would  undoubtedly  more  than  equal 
the  combined  sales  of  the  remaining  paint  houses  in  the 
country. 

367.  Conditions  to  be  Observed.   The  white  lead  or  paint 
manufacturer,  therefore,  should  give  careful  heed  to  the 
condition  of   his   mills   and   the   conditions    under  which 
they  are  operated.     Cheap  stones,  careless  or  infrequent 
dressing,  loose  adjustment,  hasty  or  careless  mixing,  will 
produce   poor   paint,   no   matter  how  good    may  be   the 
material  used.     The  heating  of  mills  and  the  use  of  water- 
cooled  mills  have  already  been  discussed  in  several  places 
in  this  book  and  need  not  be  taken  up  again  in  this  con- 
nection. 

368.  Mixing  and  Chasing.   Before  being  delivered  to  the 
grinding  mills  the  pigments  and  linseed  oil  or  other  vehicles 
are  incorporated  either  in  a  mixer  or  by  means  of  a  chaser 
and  mixer.     Chasing  the  pigments  and  oil  first,  then  plac- 
ing in  a  mixer,  is  undoubtedly  far  superior  to  mixing  alone, 
although  the  writer  is  sorry  to  say  that  the  latter  practice 
is  the  one  most  commonly  followed.     Chasing  brings  the 
pigment  particles  in  very  close  contact  with  each  other 
and  with  the  oil,  and  will  effect  a  more  thorough  distribu- 


248  THE   LEAD   AND   ZINC  PIGMENTS. 

tion  of  the  different  pigments  present  than  is  accom- 
plished in  an  ordinary  mixer.  It  is  a  well-known  fact  that 
a  paint  properly  chased,  mixed,  and  ground  will  occupy 
considerably  less  volume  than  a  paint  simply  mixed  and 
ground.  In  many  instances  when  there  is  a  rush  of  orders 
the  mixing  is  done  hastily  and  the  "  mix  "  let  down  into  the 
mill  before  all  of  the  pigment  particles  have  come  in  con- 
tact with  the  oil  and  become  thoroughly  saturated;  this 
increases  the  difficulty  of  grinding  and  increases  the  wear 
on  the  stones,  as  well  as  lessening  the  wearing  value  of 
the  paint. 

369.  Proper  Selection  of  Stones.   Every  practical  paint 
grinder  should  be  able  to  judge  the  different  stones  neces- 
sary for  the  grinding  of  various  materials,  —  as,  for  in- 
stance, ores,  which  are  sometimes  ground  into  very  fine 
particles  in  order  to  make  the  different  paints,  pastes,  or 
pigments,  —  and  furthermore  learn    to  know  the  various 
reliable  houses  furnishing  such  stones.     The  author  desires 
at  this  point  to  express  his  appreciation  for  the  valuable 
information  and  drawings  furnished  in  this  connection  by 
Paul  Oehmig  &  Co.,  who  have  had  a  wide  experience  in 
the  construction  of  mills. 

370.  Every  millstone   must    feel   sharp   to    the   touch 
and   possess   a  natural  cut.     Successful  milling  depends 
almost  entirely  upon  proper  judgment  in  selecting  these 
stones,  as  only  such  stones  as  possess  a  natural  cut  can  be 
successfully   dressed,   which  is,   of  course,   necessary   for 
grinding  the  various  materials. 

371.  Source  of   Millstones.     The    most  valuable  stone 
material  is  the  so-called  "  Fresh  Water  Quartz,"  which  is 
imbedded  in  the  chalk  deposits,  particularly  in  France,  and 
these  are  commonly  called  "  Old  Stock  French  Buhrs,"  and 
are  adapted  for  all  milling  processes.     Others  of  a  denser 
grain  are  found  near  the  mouths  of  former  hot  springs,  and 


GRINDING  WHITE  LEAD,  PASTES,  AND  PAINTS.      249 

still  others  are  found  in  low  marshy  ground,  which  con- 
tained much  vegetable  matter  at  the  time  of  their  formation. 
The  scientific  name  for  the  former  is  "  Hydro-Quartcite," 
and  for  the  latter  "  Limno-quartcite."  The  two  latter 
kinds  vary  in  structure  and  are  usually  called  "  New  Stock 
French  Buhrs."  These  are  particularly  fitted  for  the 
grinding  of  very  hard  minerals,  and  are  generally  used  for 
this  purpose,  particularly  in  the  preparation  of  paints, 
although  the  greater  majority  of  these  stones  were,  and  are, 
imported  from  France,  yet  within  the  past  twenty  years 
there  has  been  found  on  the  American  continent  a  consid- 
erable quantity  of  such  stones  which  take  the  place  of  the 
imported  ones,  many  of  which,  although  not  porous,  are 
admirably  suited  for  various  milling  purposes,  and  are 
sometimes  preferable  to  the  imported  stones. 

372.  Domestic  Stones.    The  domestic  stones  are  com- 
posed of  various  sizes  of  quartz  crystals  and  pebbles  firmly 
united  by  a  natural  cement,  and  their  hardness  and  natural 
"  cut "  suits  the  purpose,  especially  for  grinding  colors  in 
oil,  paste,  paints,  etc.    The  common  name  for  these  stones 
is  "  Esopus,"  or  "  Pebble  Grit."    The  domestic  stones  on 
account  of  the  proximity  of  the  pebbles  to  each  other  often 
become  glazed  in  grinding  pastes  and  thereby  lose  their 
natural  cut  and  in  this  respect  are  inferior  to  the  imported 
French  buhrs.     However,  for  dry  grinding,  especially  of 
medium-tempered  minerals,  the  domestic  varieties  are  con- 
sidered preferable. 

373.  Stone  Dressing.     From  the  grooved  mortars  used 
by  the  ancient  Egyptians  4000  years  B.C.,  there  developed 
the  hand  mills,  which,  as  may  be  observed  from  old  illustra- 
tions and  excavated  originals,  consisted  of  a  stone  surface 
upon  which  the  material  was  ground  with  a  pestle,  hollow 
stones  or  with  wooden  blocks.     These  later  were  developed 
into  large  circular  stone  mills,  in  which  other  than  human 


250  THE   LEAD   AND   ZINC  PIGMENTS. 

power  was  used,  as  early  as  200  years  B.C.,  as  mentioned 
in  various  historical  accounts,  and  in  later  years  similar 
mills  of  various  types  formed  a  very  important  part  of  the 
equipment  of  the  Roman  Legions,  particularly  those  of 
Caesar,  and  their  remains  were  found  centuries  afterwards 
on  the  Roman  highways.  Naturally  the  surfaces  of  these 
mills  became  worn  smooth,  and  it  was  necessary  to  invent 
an  artificial  way  of  renewing  the  cutting  surface,  and  there- 
fore arose  the  system  of  grooving  the  stones,  and  thus 
improving  and  renewing  the  grinding  surface.  This  dress- 
ing soon  took  on  a  definite  character,  and  is  found  on  many 
stones  which  are  exhibited  in  museums,  as,  for  instance,  at 
Field's  Museum  at  Chicago,  Illinois.  They  were,  however, 
less  particular  in  their  choice  of  material,  choosing  the  most 
convenient,  such  as  granite,  sandstone,  or  lava. 

374.  In  more  recent  times  it  has  become  necessary  to 
use  well  constructed  grinding  mills  in  order  to  overcome 
the  difficulties  of  grinding  various  minerals  and  paints. 
And  to-day  it  is  required  that  the  mills  must  be  easily 
adjustable  and  so  constructed  as  to  admit  of  easy  access  to 
the  grinding  stones. 

375.  Types  of  Mills.     Under  running  mills,   which  by 
their  greater  pressure  are  more  effective,   are  generally 
preferable  to  the  over  running  mills.     If  the  under  stone  is 
fixed,  and  the  upper  stone  rotates,  the  material  will  very 
slowly  be  carried  over  the  grinding  surface  of  the  bed  stone 
until  at  length  it  reaches  the  circumference  and  falls  out. 
On  the  other  hand,  if  theunderstone  is  to  be  one  that  rotates, 
all  particles  lying  on  it  will  be  hastened  along  by  centrifugal 
force,  the  grinding  surface  of  the  upper  stone  asserting  a 
pulverizing  action  on  the  larger  particles,  hindering  their 
passage  outward.     Correctly  arranged  furrows  further  the 
movement  of    the  material  and  it  therefore  follows  that 
under  runners  are  better  forwarders  and  deliverers  than 


GRINDING  WHITE   LEAD,  PASTES,  AND  PAINTS.      251 


over  runners,  and  there  is  less  chance  for  accumulation  and 
over  heating. 

376.  Best  Method  of  Dressing  Stones.     No  definite  system 
can  be  outlined  which  will  be  safe  to  follow  in  all  cases.     In 
the  grinding  of  paints  it  is  not  so  much  a  question  of  cutting 
surface  as  of  pressure  with  which  to  reduce  the  material  to 
the  desired  fineness.     The  grinding  of  cereals,  on  the  other 
hand,  necessitates  a  very  fine,  sharp  and  systematic  dressing. 
The  stones,  in  both  cases,  must  possess  a  number  of  furrows, 
which  bring  the  material  from  the  center  of  the  stones  to 
the  actual  grinding  surfaces  where  the  material  is  actually 
ground.     These  furrows  are  necessary  in  order  to  avoid 
undue  heating  of  the  material,  and  in  order  to  avoid  over- 
loading the  grinding  surface.     In  under  running  mills,  these 
furrows  should  never  be  too  deep  on  the  running  stone,  but 
on  the  stationary  stone  they  should  'be  deeper.     It  is  also 
necessary  that  the  surface  of  the  stones  be  a  little  concave, 
or  tapered  down  to  the  eye,  which  adds  to  the  efficiency 
of  the  grinding  surface.     By  following  out  the  above  sug- 
gestions it  will  be  found  that  the  mill  will  always  run  cool 
and  that  it  will  be  impossible  to  overload  the  grinding 
surface. 

377.  Adjustment   of  Grooves.     Dressing  was  originally 
done  in  circular  and  radial  grooves,  but  this  was  found  not 
to  be  practical  for  every  purpose,  for  the  reason  that  when 
two  corresponding  grooves  of  the  two  stones  come  together, 
they  should  cross  in  such  a  way  as  to  make  a  scissor-like 
movement,  and  never  cross  in  two  angles.     Figures  78  and 
79  designate  the  kinds  of  dressings  which  are  most  easily 
kept  in  order,  and  which  are  best  for  various  purposes. 
These  two  dressings  can  only  be  recommended  for  dry 
grinding. 

378.  Grinding  Pastes.     A  portion  of  Fig.  79  is  designed 
to  show  the  actual  working  of  the  two  grinding  surfaces,  as 


252 


THE   LEAD   AND   ZINC  PIGMENTS. 


FIG.  78.  —  DRESSING  FOR  PAINT  MILL. 


FIG.  79.  —  ADAPTION  OF  GRINDING  SURFACES. 


GRINDING   WHITE   LEAD,  PASTES,   AND   PAINTS.       253 

they  should  be,  and  at  which  angle  and  direction  the  two 
sets  of  grooves  cross  each  other  and  what  relation  their 
direction  has  to  the  direction  of  the  movement.  The  rela- 
tion of  the  furrows  is  shown  on  Fig.  80.  For  the  grinding 
of  colors  the  following  kinds  of  dressings  should  be  used. 
Fig.  81  is  an  illustration  of  a  French  buhrstone  of  about 
thirty  inches  in  diameter,  which  is  practically  efficient  for 
grinding  heavy  pastes,  colors,  etc.,  which  contain  a  large 
percentage  of  silicates.  The  furrows  are  quite  wide  and 
deep.  The  stones  should  be  dressed  three-eighths  of  an 


FIG.  80. — ADJUSTMENT  OF  FURROWS. 

inch  apart  and  the  grinding  face  should  not  be  over  7J  to 
8  inches.  In  order  to  facilitate  the  introduction  of  the 
material  to  be  ground,  it  is  preferable  to  deepen  the  fur- 
rows somewhat  toward  the  center,  as  well  as  deepen  the 
grinding  surface  toward  the  eye  of  the  stone.  For  the 
grinding  of  oil  colors  and  enamels  a  20-inch  mill  with 
4-inch  face  is  generally  used  (see  Fig.  82). 

379.  Use  of  Mill  Picks.  In  dressing  the  stones,  care 
should  always  be  taken  that  the  mill  picks  are  not  too 
heavy  and  are  in  proper  shape  on  the  jutting  edge  to 
avoid  splintering  and  smashing  the  grinding  surface  of  the 
stones.  The  furrows  of  the  grinding  stones  should  be  cut 


254  THE  LEAD   AND   ZINC  PIGMENTS. 

as  smooth  as  possible,  also  it  is  preferable  to  have  the 
furrows  wide  rather  than  cutting  them  in  a  ditchy-like 
appearance,  as  the  furrows  are  the  actual  transmitters  of 
the  material  to  the  grinding  surface.  If  this  style  of 
dressing  is  followed  the  life  of  the  millstone  will  be  longer 
and  a  great  deal  of  trouble  and  annoyance  prevented. 

It  will  be  noted  that  Fig.  81  does  not  show  the  furrows 
cut  to  the  edge  of   the  stone,  but   it  is  the  opinion  of 


FIG.  81.  —  DRESSING  FOB  HEAVY  GRINDING. 

several  stone  manufacturers  that  it  is  best  to  cut  these 
furrows  to  a  feather  edge  up  to  the  rim  of  the  stone,  but 
this  should  be  the  shop  practice. 

380.  Pneumatic  Dressing.  The  majority  of  the  larger 
paint  manufacturers  now  dress  their  mills  with  a  pneu- 
matic chisel,  thereby  saving  considerable  time  and  labor, 
but  the  writer  has  noticed  that  where  the  pneumatic  tool 
is  used  there  is  a  tendency  toward  careless  dressing.  This 
is  probably  due  more  than  anything  else  to  inefficient 


GRINDING  WHITE  LEAD,   PASTES,   AND  PAINTS.      255 

workmen,  as  formerly  mill  dressing  was  a  recognized  trade, 
commanding  good  wages,  and  from  long  experience  the 
men  came  to  understand  all  of  the  fine  points  and  require- 
ments of  the  trade,  but  with  the  advent  of  the  pneumatic 
tool  the  mills  have  been  intrusted  to  the  care  of  cheaper 
and  less  experienced  workmen  who  have  made  little  or 
no  study  of  paint  grinding. 

381.   Frequency  of  Dressing.   The  frequency  with  which 
mills  should  be  dressed  is  a  much  debated  question  and 


FIG.  82.  —  DRESSING  FOU  20  INCH  MILL. 

depends  to  a  large  extent  on  the  nature  of  the  material 
to  be  ground  and  the  tightness  of  the  tension  used.  One 
of  the  leading  manufacturers,  whose  lead  and  paste  mills 
are  in  almost  continuous  operation,  takes  down  his  mills 
for  dressing  about  once  a  year,  varying  as  occasion  may 
demand  between  six  and  eighteen  months.  The  inevita- 
ble consequence  was  that  the  stones  had,  long  before  the 
time  of  dressing,  worn  smooth,  the  grooves  having  entirely 
disappeared,  and  in  order  to  secure  the  customary  output 
the  tension  had  been  released  to  such  an  extent  that  the 
stones  exerted  little  if  any  grinding  or  crushing  force  on 


256  THE  LEAD  AND   ZINC  PIGMENTS. 

the  pigment  particles.     It  is  needless  to  add  that  his  prod- 
ucts plainly  showed  lack  of  grinding. 

382.  Paint  grinders  who  have  given  the  matter  careful 
study  dress  their  paste,  semi-paste  and  lead  mills  every 
hundred  to  two  hundred  grinding  hours,  varying  somewhat 
as  occasion  may  require.     Strictly  pure  leads  which  are 
of  very  fine  texture  are  not  as  hard  on  the  mill  and  con- 
sequently it  may  go   for  a  considerably  longer  period. 
Much  of  course  depends  on  the  hardness  and  nature  of  the 
stones  themselves.     The  above  figures  are  based  on  an 
average  grade  of  domestic  stones.     The  various  lead  and 
zinc  pigments  are  easy  to  grind  as  compared  with  ochres, 
metallics,  e.g.,  Princes,  and  the  various  greens,  etc. 

383.  Types   of   Dressing.   As   the   dressing   of   mills   is 
essentially  the  development  of    a  scissor-like   movement 
between  the  surfaces,  the  dressing  of  mills  for  the  grind- 
ing of  various  paint  products   resolves  itself   into  a  fine 
dressing  for  oil  color  and  coach  color  mills,  which  are  usu- 
ally about  twenty  inches  in  diameter,  having  a  medium 
face  and  furrows  of  medium  draft,  while  large  mills  for 
heavy  pastes  require  a  much  heavier,  deeper  and  sharper 
edged  dressing  with  sufficient  draft  to  move  the  product 
swiftly  between  the  grinding  faces  to  the  edge.     With  a 
freshly  dressed  mill  there  is  always  a  strong  tendency  of 
heating,  which  by  expansion  tightens  the  tension,  increas- 
ing the  friction  and  thus  making  the  heating  more  rapid. 
Especial  attention  should  be  given  a  freshly  dressed  mill 
and  the  tension  released  as  the  mill  begins  to  warm  up. 
It  is  almost  unnecessary  to  state  that  all  mills  should  be  as 
efficiently  water  cooled  as  possible. 

384.  Speed  of  Mills.  As  in  the  above  instance  no  definite 
rules  can  be  laid  down.     Some  factories  are  running  their 
mills  at  a  rate  of  from  55  to  60  r.p.m.  with  very  satisfactory 
results,  while  others  do  not  run  over  35  to  40  r.p.m.,  as  it 


GRINDING    WHITE  LEAD,  PASTES,  AND  PAINTS.         257 

largely  depends  upon  how  the  product  to  be  ground  is 
treated  before  it  is  given  to  the  mill,  also  upon  the  nature 
of  the  product,  and  upon  the  construction  of  the  mills 
used  for  grinding  same.  Mills  grinding  very  heavy  pastes 
should  run  slower,  35  to  40  r.p.m.,  while  mills  grinding  an 
easy-to-finish  or  liquid  paint,  can  run  faster,  50  to  60  r.p.m. 


CHAPTER  XXV. 

ANALYSIS  OF  COMMERCIALLY  PURE   WHITE  LEADS. 

385.  Sulphur    Dioxide.   In    the    manufacture    of    quick 
process  white  leads,  where  the  carbon  dioxide  is  obtained 
from  fuel  gases,  it  is  liable  to  contain  sulphur  compounds 
which  will  remain  in  the  white  lead  combined  in  the  form 
of  sulphite  of  lead. 

386.  The  sulphur  dioxide  may  be  estimated  by  treating 
10  grams  of  the  pigment  with  50  c.c.  of  water  and  25  c.c. 
of  hydrochloric  acid.    Allow  to  stand  5  minutes  and  titrate 
with  hundredth  normal  iodine  solution  as  described  under 
the  estimation  of  sulphur  dioxide  in  zinc  pigments.     The 
same  objections  apply  to  its  presence  in  white  lead  as  in 
zinc  oxides. 

387.  Sandy   Lead.1     "  A   certain   degree   of   density   is 
always  desired  in  white  lead,  since  both  the  corroder  and 
the  grinder  know  that  the  smaller  the  amount  of  oil  required 
to  bring  a  given  lead  to  paste  form,  the  cheaper  it  is  for 
him,  since  the  average  price  per  pound  of  linseed  oil  is 
greater  than  that  of  dry  lead,  while  the  same  pigment  is 
equally  sought  after  by  the  consumer,  since  he,  too,  desires 
density  and  opacity  in  this  pigment.      However,  efforts 
in  this  direction  are  not  infrequently  carried  too  far,  with 
the  result  of  a  crystalline  overcorroded  lead,  which  settles 
and  hardens  badly.     Such  lead  causes  loss  and  trouble  both 
to  the  grinder  and  the  consumer. 

388.  Determination.     "  Based  upon  the  undesirable  fea- 
ture of  settling,  a  comparative  separation  is  easily  made. 

1  Hooker,  Treatise  on  White  Lead,  page  24. 
258 


ANALYSIS  OF  COMMERCIALLY  PURE  WHITE  LEADS.     259 

A  fairly  large  sample,  say  100  grams,  is  taken.  This  if  in 
paste  form  is  thinned  with  benzine  and  run  through  a  fine 
bolting  cloth.  Any  paint  skins  are  retained,  but  all  of 
the  lead  should,  when  sufficiently  thinned,  wash  through 
a  fine  bolting  cloth.  The  very  thin  paint  is  now  thor- 
oughly stirred  and  allowed  to  settle  for  a  short  time  only. 
Nearly  all  of  the  benzine  is  now  poured  off  and  then  the 
washing  of  the  sediment  with  benzine  repeated  until  the 
benzine  comes  off  nearly  clear,  leaving  the  '  sand  '  alone 
as  a  residue."  While  present  in  all  commercial  lead,  the 
amount  should  be  small,  scarcely  exceeding  2.5  per  cent; 
objectionable  samples  will  frequently  show  much  more,  at 
times  over  10  per  cent. 

389.  Tan-bark.   The    determination    of    tan-bark    and 
other  organic  matter  is  seldom  required.     It  may,  however, 
be  made  by  dissolving  50  grams  of  the  sample  in  75  c.c.  of 
nitric  acid  diluted  with  250  c.c.  of  water.     Filter  through 
a  weighed  Gooch  crucible,  provided  with  a  disk  of  filter 
paper  on  the  top  of  the  asbestos  felt,  wash  thoroughly  dry 
and  weigh.     The  amount  present  should  not  exceed  one- 
tenth  of  one  per  cent,  according  to  Hooker. 

390.  Sulphate  of  lead,  which  may  be  present  in  some  of 
the  quick-process  leads,  would  largely  remain  undissolved 
in  the  nitric  acid  solution  and  unless  removed  would  be 
weighed  up  as  tan-bark,  etc.     When  present  it  may  be 
dissolved  by  placing  the  Gooch  crucible  and  contents  in  a 
small  beaker  containing  acid  ammonium  acetate  for  a  few 
minutes,  after  which  the  crucible  is  placed  in  the  holder, 
washed  with  a  further  quantity  of  acetate  solution,  then 
with  a  little  warm  water,  and  dried  as  before. 

391.  Metallic  Lead.   Like  the  previous  determination  it 
is  seldom  made.     Occasionally  in  poorly  prepared  white 
leads  a  sufficient  amount  may  be  present  to  warrant  a 
determination;  in  which  case  it  is  best  made  in  conjunction 


260  THE   LEAD   AND   ZINC  PIGMENTS. 

with  the  determination  of  "  sandy  lead/'  which,  after 
being  weighed  up,  is  carefully  dissolved  in  dilute  nitric 
acid,  the  operation  being  checked  the  moment  the  sandy 
white  lead  has  dissolved  by  dilution  with  a  large  quantity 
of  water.  The  particles  of  metallic  lead  are  but  very 
slightly  acted  upon  by  acid  and  may  be  filtered  off  on  to  a 
weighed  Gooch  crucible,  washed  thoroughly,  dried  and 
weighed.  The  amount  found  should-  not  exceed  one- 
tenth  of  one  per  cent. 

392.  Lead  Sulphate.   This  impurity  may  be  present  in 
small  quantities  in  white  leads  prepared  by  the  newer 
processes  and  sometimes  in  old  Dutch  process  lead  in  the 
settling  tanks  and  wash  water  tanks.     When  present  in 
quantities  less  than  one-half  of  one  per  cent  it  should 
not  be  considered  as  seriously  objectionable. 

393.  Determination.   Dissolve  1  gram  in  water  25  c.c., 
ammonia  10  c.c.,  hydrochloric  acid  in  slight  excess. 

Dilute  to  200  c.c.,  and  add  a  piece  of  aluminum  foil 
which  should  about  cover  the  bottom  of  the  beaker.  It  is 
important  that  this  be  held  at  the  bottom  by  a  glass  rod. 
Boil  gently  until  the  lead  is  precipitated.  Completion  of 
this  is  shown  by  the  lead  ceasing  to  coat  or  cling  to  the 
aluminum.  Decant  through  a  filter,  pressing  the  lead 
sponge  into  a  cake  to  free  it  from  solution.  Add  to  filtrate 
a  little  sulphur-free  bromine  water,  boil  until  the  bromine 
is  expelled,  add  15  c.c.  of  barium  chloride,  boil  10  minutes, 
fifter,  wash  with  hot  water,  ignite  and  weigh  as  barium 
sulphate.  Calculate  to  lead  sulphate  by  multiplying  by 
1.3  as  a  factor. 

394.  Volumetric  Estimation  of  Lead,  Method  I.1   Dissolve 
1  gram  in  15  c.c.  nitric  acid,  specific  gravity  1 .20,  neutralize 
the   solution   with   ammonia  in   excess,   and   then   make 
strongly   acid   with   acetic   acid.     It   is   then   boiled   and 

1  Wainwright,  J.,  Am.  Chem.  Soc.;  vol.  19,  page  389. 


ANALYSIS  OF  COMMERCIALLY  PURE  WHITE  LEADS.    261 

standard  potassium  bichromate  solution  in  sufficient 
quantity  to  precipitate  nearly  all  the  lead  is  run  in  from 
a  burette.  The  liquid  is  boiled  until  the  precipitate  be- 
comes orange  colored.  The  titration  is  continued,  one- 
half  c.c.  or  so  at  a  time,  the  solution  being  well  stirred 
after  each  addition  of  bichromate  until  the  reaction  is 
almost  complete,  which  can  be  observed  by  the  sudden 
clearing  up  of  the  solution,  the  lead  chromate  settling 
promptly  to  the  bottom  of  the  beaker;  this  will  usually 
occur  within  1  c.c.  of  the  end  of  the  reaction.  The  titra- 
tion is  then  finished,  the  end  point  being  indicated  by  the 
use  of  a  silver  nitrate  as  an  outside  indicator,  on  a  white 
plate. 

The  solution  of  the  lead  salt  should  be  as  concentrated 
as  possible  before  titration  and  decidedly  acid  with  acetic 
acid.  The  titration  should  be  performed  in  a  solution 
kept  at  all  times  as  near  the  boiling  point  as  possible. 

395.  Potassium  Bichromate  Solution.   This  should  be  of 
such  strength  that  1  c.c.  equals  approximately  0.01  gram 
of  metallic  lead,  and  should   be  standardized   against  a 
weighed  amount  of  pure  metallic  lead  as  described  above. 

396.  Silver    Nitrate    Solution.     Dissolve    2.5  grams   of 
silver  nitrate  in  100  c.c.  of  water. 

NOTE. —  This  method  is  applicable  for  determination  of  lead  in  red 
lead,  the  solution  being  effected  with  nitric  acid,  boiling,  and  adding 
dilute  oxalic  acid  drop  by  drop  until  the  lead  oxide  formed  is  completely 
dissolved. 

397.  Volumetric  Estimation  of  Lead,  Method  II.1     Dis- 
solve 0.5  to  1  gram  of  the  pigment  in  acetic  acid  if  white 
lead,  if  lead  sulphide,  dissolve  in  nitric  acid,  dilute  with 
25  c.c.  cold  water,  add  strong  ammonia  until  just  alkaline 
to  litmus  paper,  then  make  distinctly  acid  with  strong 
acetic  acid. 

1  Alexander's  Method,  Ore  Analysis,  Low,  page  113. 


262  THE   LEAD   AND    ZINC  PIGMENTS. 

398.  Heat   to   boiling,   dilute  to   about   200   c.c.   with 
boiling  hot  water,  and  titrate  with  standard  ammonium 
molybdate  solution.     Reserve  about   10  c.c.   of  the  hot 
solution  in  a  small  beaker,  run  in  molybdate  solution  into 
the  large  beaker  from  a  burette,  with  constant  stirring, 
until  a  drop  placed  in  contact  with  a  drop  of  tannic  acid 
solution  on  a  white  plate  gives  a  brown  or  yellow  tinge. 
Add  the  10  c.c.  reserved  and  finish  the  titration  carefully  at 
the  rate  of  two  drops  addition  at  a  time.     When  the  final 
yellow  tinge  is  obtained,  it  is  probable  that  some  of  the  im- 
mediately preceding  test  drops  may  have  developed  a  tinge 
also.   If  such  is  the  case  deduct  the  volume  of  two  drops  from 
each  test  showing  a  color  from  the  final  burette  reading. 

399.  Molybdate  Solution.   Prepare  a  solution  of  ammo- 
nium molybdate  1  c.c.  of  which  is  equal  to  approximately 
.01  gram  of  lead.     Standardize  against  a  weighed  amount 
of   chemically   pure  lead,   dissolving  in   nitric   acid   and 
treating  as  described  above. 

400.  Tannic  Acid  Solution.    Dissolve  0.5  gram  of  tannic 
acid  in  100  c.c.  water. 

401.  Carbon  Dioxide.  The  amount  of  carbon  dioxide 
in  white  lead  can  be  most  accurately  estimated  by  means 
of  Knorr's  apparatus. 

This  apparatus  employs  only  ground-glass  joints,  and 
may  be  quickly  made  ready  for  use  or  taken  to  pieces 
and  packed  away.  On  the  other  hand,  it  is  inflexible 
and  must  be  carefully  handled.  A  is  distilling  flask  fitted 
to  condenser  by  a  ground-glass  stopper;  B,  reservoir  con- 
taining acid;  C,  soda-lime  tube;  D,  condenser;  E,  cal- 
cium chloride  tube;  F,  U-tube  filled  with  pumice  stone 
moistened  with  sulphuric  acid,  followed  by  a  calcium- 
chloride  tube  G.  The  three  soda-lime  tubes  H,  H,  H 
are  followed  by  a  calcium  chloride  tube  K,  which  is  con- 
nected with  an  aspirator  at  L. 


ANALYSIS  OF  COMMERCIALLY  PURE  WHITE  LEADS.    263 

The  calcium  chloride  and  soda  lime  employed  should  be 
finely  granulated  and  freed  from  dust  with  a  sieve. 

402.  One  gram  of  the  sample  to  be  examined  is  placed 
in  the  distilling  flask,  which  must  be  perfectly  dry.  The 
flask  is  closed  with  a  stopper  carrying  the  tube  connecting 
with  the  absorption  apparatus  and  also  with  the  funnel 
tube.  The  tubes  in  which  the  carbon  dioxide  is  to  be 
absorbed  are  weighed  and  attached  to  the  apparatus.  In 
case  two  Liebig  bulbs  are  employed,  one  for  potassium 
hydroxide  and  the  other  for  sulphuric  acid,  to  absorb  the 
moisture  given  up  by  the  potassium  hydroxide  solution,  it 


FIG.  83.  —  KNORR'S  APPARATUS. 

will  be  necessary  to  weigh  them  separately.  If  soda-lime 
tubes  are  employed  it  will  be  found  advantageous  to  weigh 
them  separately  and  fill  the  first  tube  anew  when  the 
second  tube  begins  to  increase  in  weight  materially.  The 
bulb  B  is  nearly  filled  with  hydrochloric  acid  (sp.  gr.  1.1), 
and  the  guard  tube  C  placed  in  position.  The  aspirator 
is  now  started  at  such  a  rate  that  the  air  passes  through 
the  Liebig  bulbs  at  the  rate  of  about  two  bubbles  per 
second.  The  stopper  of  the  funnel  tube  is  opened  and  the 
acid  allowed  to  run  slowly  into  the  flask,  care  being  taken 
that  the  evolution  of  the  gas  shall  be  so  gradual  as  not  to 
materially  increase  the  current  through  the  Liebig  bulb. 


264  THE   LEAD   AND   ZINC  PIGMENTS. 

403.  After  the  acid  has  all  been  introduced,  the  aspira- 
tion is  continued,  when  the  contents  of  the  flask  are  gradu- 
ally heated  to  boiling,  the  valve  in  tube  B  being  closed. 
While  the  flask  is  being  heated  the  aspirator  tube  may 
be  removed,  although  many  analysts  prefer  when  using 
ground -glass  joints  to  aspirate  during  the  entire  opera- 
tion.    The  boiling  is  continued  for  a  few  minutes  after  the 
water  has  begun  to  condense  in  D,  when  the  flame  is 
removed,  the  valve  in  the  tube  B  opened,  and  the  appa- 
ratus allowed  to  cool  with  continued  aspiration.     The  ab- 
sorption tubes  are  then  removed  and  weighed,  the  increase 
in  weight  being  due  to  carbon  dioxide. 

404.  Where  extreme  accuracy  is  desired  the  carbon  diox- 
ide after  passing  through  the  condenser  should  pass  through 
a  U-tube  filled  with  calcium  chloride,  a  (J-tube  filled  with 
lumps  of  dehydrated  copper  sulphate  moistened  with  sul- 
phuric acid  (sp.  gr.  1.84),  and  then  through  a  U-tube  filled 
with  pumice  stone  moistened  with  sulphuric  acid  before 
being   absorbed   by  soda-lime.     The   air   used    for   aspi- 
rating should  also  pass  through  a  large  U-tube  filled  with 
soda  lime  before  passing  through  the  small  soda-lime  tube  C. 
In  order  to  make  the  apparatus  compact  the  soda-lime  tubes 
may  be  laid  side  by  side  on  a  small  rack  constructed  for 
the  purpose,  the  soda-lime  tubes  being  connected  with  each 
other  by  small  U-shaped  glass  tubing  connections. 

405.  Acetic  Acid  in  White  Lead.1   "  In  the  manufacture 
of  white  lead  by  any  process  involving  the  use  of  acetic 
acid,  a  certain  portion  of  the  acetic  acid  seems  to  be  bound 
firmly  so  that  it  cannot  be  washed  out  in  any  ordinary 
process  of  manufacture.     The  amount  of  the  acetic  acid 
which  is  fixed  by  the  white  lead  depends  largely  upon  the 
quantity  used  in  the  process  of  manufacture.     The  Navy 
Yard  specifications  demand  a  white  lead  which  shall  not 

1  G.  W.  Thompson,  J.  Soc.  Chem.  Ind.,  vol.  xxiv,  No.  9. 


ANALYSIS  OF  COMMERCIALLY  PURE  WHITE  LEADS.     265 

contain  '  acetate  in  excess  of  fifteen  one-hundredths  of 
1  per  cent  of  glacial  acetic  acid.'  It  seems  reasonable,  fur- 
thermore, that  whether  the  acetic  acid  is  objectionable  or 
not,  the  intelligent  purchaser  of  white  lead  should  be  en- 
abled, as  far  as  possible,  to  know  what  he  is  buying,  and 
perhaps  trace  back  results  to  some  definite  cause. 

406.  "  Ordinary  lead  acetate  solution  will  take  up  vary- 
ing amounts  of  lead  oxide  to  form  basic  lead  acetate.     The 
more  concentrated  the  lead  acetate  solution  is,   the  less 
basic  will  be  the  formed  acetate;  for  instance,  the  ordinary 
pharmacopoeia   solution  —  '  Liquor    Plumbi    Subacetatis  ' 

—  contains  two  equivalents  of  lead  to  one  of  acetic  acid, 
and,  while  this  solution  may  be  made  more  basic  than 
this  by  adding  an  excess  of  litharge,  the  amount  of  litharge 
which  it  will  take  into  solution  in  excess  of  that  required 
to  form  the  pharmacopoeia  solution  is  comparatively  small." 

407.  "  Working  with  dilute  solutions  of  lead  acetate, 
however,  solutions  can  be  obtained  containing  as  much  as 
ten  equivalents  of  lead  to  one  of  acetic  acid.     These  very 
basic  dilute  solutions  may,  however,  be  regarded  by  some 
as  supersaturated  solutions,  for  the  reason  that  the  basic 
lead  tends  to  separate  out  on  slight  provocation,  carrying 
with  it  some  acetic  acid.     If  this  very  basic  lead  acetate, 
which  separates  out,  is  washed  with  distilled  water,  it 
appears  to  form  a  colloidal  solution,  from  which  the  basic 
lead  is  readily  precipitated  in  the  presence  of  suspended 
inert  material,  and  especially  in  the  presence  of  electro- 
lytes.    Ordinary  water  is  usually  used  for  washing  white 
lead,  and,  as  this  water  contains  more  or  less  saline  sub- 
stances, any  of  this  extremely  basic  acetate  that  is  present 
will  be  precipitated  with  the  white  lead,  and  go  into  the 
finished  product." 

408.  "  Determination.   18  grams  of  the  dry  white  lead  are 
placed  in  a  500-c.c.  flask,  this  flask  being  arranged  for  con- 


266  THE  LEAD  AND   ZINC  PIGMENTS. 

nection  with  a  steam  supply,  and  also  with  an  ordinary 
Liebig  condenser.  To  this  white  lead  is  added  40  c.c.  of 
syrupy  phosphoric  acid,  18  grams  of  zinc  dust,  and  about 
50  c.c.  of  water.  The  flask  containing  the  material  is  heated 
directly  and  distilled  down  to  a  small  bulk.  Then  the  steam 
is  passed  into  the  flask  until  it  becomes  about  half  full  of 
condensed  water,  when  the  steam  is  shut  off  and  the  original 
flask  heated  directly  and  distilled  down  to  the  same  small 
bulk,  this  operation  being  conducted  twice.  The  dis- 
tillate is  then  transferred  to  a  special  flask  and  1  c.c.  of 
syrupy  phosphoric  acid  added  to  insure  a  slightly  acid 
condition." 

409.  "The  flask  is  then  heated  and  distilled  down  to  a 
small  bulk  —  say,  20  c.c.     Steam  is  then  passed  through 
the  flask  until  it  contains  about  200  c.c.  of  condensed  water, 
when  the  steam  is  shut  off  and  the  flask  heated  directly. 
These  operations  of  direct  distillation  and  steam  distillation 
are  conducted  until  10  c.c.  of  the  distillate  require  but  a 
drop  of  N/10  alkali  to  produce  a  change  in  the  presence  of 
phenolphthalein.     Then  the  bulk  of  the  distillate  is  titrated 
with  N/10  sodium  hydroxide,  and  the  acetic  acid  calculated. 
It  will  be  found  very  convenient  in  this  titration,  which 
amounts  in  some  cases  to  600  to  700  c.c.,  to  titrate  the  dis- 
tillate when  it  reaches  200  c.c.,  and  so  continue  titrating 
every  200  c.c.  as  it  distills  over." 

410.  "  Conclusions.    The  details  in  this  described  method, 
as  regards  the  supply  of  steam  from  an  outside  flask,  its 
condensation  and  subsequent  evaporation,  are  not  essential 
to  the  process,  but  can,  of  course,  be  modified  so  as  to  con- 
form to  the  ordinary  method  of  distilling  acetic  acid  from 
acetate  of  lime.     If  the  white  lead  contains  appreciable 
amounts  of  chlorine,  it  is  well  to  add  some  silver  phosphate 
to  the  second  distillation  flask,  and  not  to  carry  the  dis- 
tillation from  this  flask  too  far  at  any  time.     If  the  dry 


ANALYSIS   OF  COMMERCIALLY  PURE  WHITE  LEADS   267 

white  lead  under  examination  has  been  obtained  by  extrac- 
tion as  a  residue  from  white  lead  paste,  it  is  well  that  this 
extraction  should  be  exceedingly  thorough,  as  otherwise 
fatty  acids  may  be  held  and  distilled  with  the  acetic  acid. 
Even  then  they  will  not  interfere  with  the  final  titration, 
as  they  may  be  filtered  from  the  distillate  before  titration, 
should  that  be  desired." 


CHAPTER  XXVI. 

ANALYSIS  OF  THE   ZINC  PIGMENTS. 

411.  Moisture.    Two  grams  of  the  pigment  are  weighed 
out  on  to  a  watch  glass,  provided  with  a  cover  glass  and  clip, 
dried  for  two  hours  in  a  steam  oven,  the  cover  glass  placed 
in  position  and  held  by  the  clip,  the  glasses  cooled  in  the 
desiccator  and  weighed.     Loss  in  weight  represents  the 
amount  of  moisture  in  the  pigment. 

412.  Silica.    Weigh  one  gram  of  pigment  into  a  250-c.c. 
covered  beaker,  add  25  c.c.  of  concentrated  hydrochloric 
acid,  heat  gently  for  five  minutes,  or  until  the  pigment  has 
dissolved  (if  lead  sulphate  is  present  in  considerable  quan- 
tity, this  may  take  quite  a  few  minutes),  add  50  c.c.  hot 
water,  and  continue  the  heating  for  about  five  minutes 
longer.     Filter  boiling  hot  with  the  aid  of  suction,  washing 
thoroughly  with  boiling  water  so  as  to  thoroughly  remove 
all  the  lead  and  zinc  salts  from  the  filter-paper.     The  filter- 
paper  and  any  residue  of  silica  is  burned,  ignited  and 
weighed  in  the  usual  manner.     Any  weighable  residue  is 
reported  as  silica. 

413.  This  treatment  may  give  results  that  are  slightly 
low,  owing  to  the  slight  solubility  of  silica  in  strong  hydro- 
chloric acid,  but  for  commercial  purposes  this  slight  error 
may  be  neglected.     In  carefully  prepared  zinc  pigments 
the  amount  of  silica  present  will  be  unweighable ;  even  with 
careless  processing  the  amount  will  seldom  exceed  a  very 
few  hundredths  of  one  per  cent. 

414.  Sulphur  Dioxide.     Weigh  3  grams  of  the  pigment 
into  a  250-c.c.  beaker;  add  100  c.c.  of  distilled  water,  that 
has  been  recently  boiled  and  cooled.     Add  5  c.c.  of  concen- 

268 


ANALYSIS   OF  THE   ZINC  PIGMENTS.  269 

t rated  sulphuric  acid,  stir  thoroughly  and  allow  to  stand 
15  minutes.  Titrate  with  standard  hundredth  normal 
iodine  solution,  using  starch  paste  as  an  indicator. 

1  c.c.  hundreth  normal  iodine  =  0.00032  gram  sulphur 
dioxide. 

415.  Preparation   of  Reagents  —  Iodine   Solution.     Dis- 
solve 1.268  grams  of  pure  iodine  and  1.8  grams  of  potassium 
iodide  in  about  150  c.c.  of  water  in  a  graduated  liter  flask. 
After  solution,  fill  to  the  mark  with  water  that  has  been 
freshly  boiled. 

416.  Sodium     Thiosulphate.     Dissolve     2.5     grams     in 
recently  boiled  distilled  water  and  make  up  to  one  liter. 
Preserve  in  a  brown  glass  bottle  or  one  that  has  received  a 
liberal  coat  of  asphaltum. 

417.  Starch  Paste.     One  gram  of  starch  is  boiled  in 
200  c.c.  of  distilled  water. 

418.  Standardizing   the   Sodium   Thiosulphate   Solution. 
Pipette  20  c.c.  of  standard  potassium  dichrornate  solution 
in  a  250-c.c.  beaker;  add  10  c.c.  of  a  15-per  cent  solution  of 
potassium  iodide.     Add  to  this  5  c.c.  of  strong  hydro- 
chloric acid.     Allow  the  solution  of  thiosulphate  to  run  in 
slowly  from  a  burette  until  the  yellow  color  has  almost 
disappeared.    Add  a  few  drops  of  starch  paste  and  continue 
the  addition  of  thiosulphate  with  constant  stirring  until 
the  blue  color  just  disappears.     The  burette  reading  is  then 
made  and  the  value  of  the  thiosulphate  calculated. 

419.  Standard  of  Acceptance.   A  good  grade  of  zinc  oxide 
should  contain  only  a  trace  of  sulphur  dioxide.     Many 
paint  chemists  reject  oxides  containing  more  than  six  hun- 
dred ths  of  one  per  cent.    The  reason  for  this  is  that  the 
sulphur  dioxide  affects  the  character  of  the  linseed  oil 
very  strongly,  causing  the  paint  to  thicken  and  ultimately 
"  liver  "  in  the  package.     This  may  be  shown  in  an  ex- 
perimental way  by  dividing  a  sample  of  zinc  oxide  into 


270  THE   LEAD   AND   ZINC  PIGMENTS. 

two  parts,  exposing  one  part  to  an  atmosphere  of  sulphur 
dioxide,  then  spreading  equal  amounts  of  both  samples  on 
a  glass  plate  and  mixing  to  a  paste  with  the  same  number 
of  drops  of  oil  in  exactly  the  same  manner.  It  will  be 
found  that  the  sample  containing  the  sulphur  dioxide  will 
be  thicker  and  stiffer  than  the  other,  showing  the  effect  of 
the  sulphur  dioxide  on  the  oil. 

420.  Reaction  with  Rosin  Products.   In  the  presence  of 
rosin  products  of  any  kind,  such  as  are  often  used  in  the 
driers  of  mixed  paints,  sulphur  dioxide  acts  as  a  contact 
agent  of  great  strength,  causing  changes  all  out  of  propor- 
tion to  the  amount  present,  often  resulting  in  hardening, 
"  washing  "  of  the  paint  film,  "  livering  "  in  the  package, 
etc.     These  results  will  be  influenced  to  a  considerable 
degree  by  the  acidity,  moisture,  and  temperature  of  the 
paint,  and  hence  no  hard  and  fast  deductions  can  be  made 
as  to  what  may  .be  expected  of  any  particular  paint  con- 
taining sulphur  dioxide  in  excess  of  the  prescribed  amount. 

421.  Zinc    Sulphate.     Ten   grams    of  the   pigment   are 
weighed  into  a  250-c.c.  Erlenmeyer  flask,  100  c.c.  of  boil- 
ing water  added.     The  contents   of  the  flask  are  then 
shaken  thoroughly  for  several  minutes  and  filtered  and 
the  residue  on  the  filter  paper  washed  with  several  por- 
tions of  boiling  water.     The  soluble  zinc  in  the  filtrate  is 
then  titrated  as  described  under  the  Estimation  of  Zinc 
by   titration  with  ferrocyanide,   and   calculated   to   zinc 
sulphate. 

422.  It  is  not  advisable  to  boil  the  zinc  oxide  pigment 
with  the  water,  as  interaction  may  occur  between  the  zinc 
oxide  and  any  lead  sulphate  present,  resulting  in  the  for- 
mation of  more  zinc  sulphate.     Neither  is  it  wise  to  esti- 
mate  the   soluble   combined   sulphuric    acid   in   the   hot 
aqueous  filtrate  and  calculate  to  zinc  sulphate,  as  there 
often  seems  to  be  an  excess  over  what  is  required  to  form 


ANALYSIS   OF  THE  ZINC  PIGMENTS.  271 

the  normal  sulphate  of  zinc  and  hence  the  results  are  apt 
to  be  too  high. 

423.  Effect.   Zinc  sulphate  is  not  considered  by  many 
paint  chemists  to  be  as  objectionable  in  zinc  pigments  as 
sulphur  dioxide,  and  is  often  permitted  in  amounts  under 
one  per  cent.     In  amounts  above  one  per  cent  it  seems  to 
act  as  an  astringent  on  the  oil  when  used  in  the  prepara- 
tion of  mixed  paints,  tending  to  prevent  the  proper  pene- 
tration of  the  wood,  especially  if  the  paint  has  been  ground 
for  some  length  of  time.     A  prominent  paint  chemist  dis- 
cusses its  effect  as  follows:    "  The  action  of  zinc  sulphate 
is  two-fold :  first,  as  an  astringent  upon  the  oil  and  tending 
to  cause  a  distinct  demarcation  between  two  coats;  and 
second,  that  of  a  contact  agent,  facilitating  reaction  be- 
tween the  different  pigments.     The  visible  results  of  its 
presence  are  peeling  and  '  washing.'     Apparently,  rather 
more  than  the  normal  amount  of  moisture  must  be  present 
to  cause  its  activity,  and  if  the  paint  coat  has  set  under 
dry  or  normal  conditions,  the  zinc  sulphate  produces  no 
apparent   effect."     In  the   exposure  tests    conducted  by 
the  author,  the  worst  cases  of  "  washing  "  have  occurred 
with  zinc  pigments  in  which  the  sulphur  dioxide  was  less 
than  one  one-hundredth  of  a  per  cent  and  the  zinc  sulphate 
between  one  and  one  and  one-half  per  cent. 

424.  Lead.   The  lead  present  in  zinc  pigments  is  usually 
in  the  form  of  sulphate  and  may  be  estimated  by  either  of 
the  following  methods. 

425.  Method  I.   The  filtrate  from  the  silica,  which  need 
not  exceed  100  c.c.  in  volume  if  the  washing  has  been 
judiciously  conducted  by  suction  or  the  hydrochloric  acid 
solution,  if  silica  is  absent,  is  evaporated  very  nearly  to 
dry  ness  in  an  uncovered  beaker  on  the  hot  plate,  avoiding 
actual  boiling,  10  c.c.  of  warm  water  added  and  evapo- 
rated again  nearly  to  dryness  in  order  to  expel  the  hydro- 


272  THE  LEAD  AND  ZINC  PIGMENTS. 

chloric  acid.  Cool,  add  30  c.c.  dilute  sulphuric  acid,  heat  to 
boiling  for  five  minutes  in  covered  beaker,  cool,  add  50  c.c. 
of  alcohol  and  allow  to  stand  one-half  hour  or  until  all  of 
the  lead  sulphate  is  precipitated  from  solution.  Filter 
through  a  weighed  Gooch  crucible,  washing  thoroughly 
with  50  per  cent  alcohol,  until  the  precipitate  is  entirely 
freed  from  zinc  sulphate.  Dry  on  hot  plate,  heat  gently 
over  a  Bunsen  burner,  cool  in  desiccator,  and  weigh  as 
lead  sulphate.  If  heated  over  the  flame  before  drying,  a 
portion  of  the  lead  is  liable  to  be  reduced  to  lead  oxide  by 
the  alcohol,  and  the  weight  will  be  low. 

426.  Method  II.   The  lead  may  be  separated  from  the 
zinc  in  a  solution  barely  acid  with  hydrochloric  acid,  by 
hydrogen   sulphide,    the   precipitated   lead   sulphide   dis- 
solved in  nitric  acid  and  titrated  with  standard  molybdate 
or  bichromate  solution   as   described   in  Chapter   XXX, 
Analysis  of  Combination  White  Leads,  and  White  Paints. 

427.  Method   III.    The  amount  of  lead  sulphate  may  be 
rapidly  estimated  by  dissolving  a  weighed  amount  of  the 
pigment  in  dilute  acetic  acid,  filtering  on  to  a  weighed 
Gooch  crucible,  washing  with  warm  water,  heating  gently, 
and  weighing  the  lead  sulphate  direct.     Lead  sulphate 
being  slightly  soluble  in  acetic  acid  the  results  will  be 
somewhat   low    and   can  only  be   considered  as  roughly 
approximate. 

428.  Total  Zinc.   The   zinc   can  be   rapidly   and   accu- 
rately estimated  volumetrically  by  the  following  methods. 

429.  I.   Potassium  Ferrocyanide  Method.  —  Preparation 
of  reagents. 

430.  Standard    Zinc    Solution.      Dissolve    10  grams;  of 
chemically  pure  zinc  in  hydrochloric  acid  in  a  graduated 
liter  flask,  add  50  grams  of  ammonium  chloride  and  "make 
up  to  one  liter.  '  r  : 

1  c.c.  =  0.01  gram  zinc  or  0.01245  gram  zinc  oxide;  :  ^ 


ANALYSIS   OF  THE   ZINC  PIGMENTS.  273 

431.  Standard    Potassium    Ferrocyanide    Solution.   Dis- 
solve 46  to  48  grams  of  crystallized  potassium  ferrocyanide 
in  water,  make  up  to  1000  c.c. 

432.  Uranium  Nitrate  Solution.     Dissolve  15  grams  of 
uranium  nitrate  in  100  c.c.  of  water. 

433.  Standardizing  the  Ferrocyanide  Solution.   To  deter- 
mine  the   value   of   the   potassium-ferrocyanide   solution, 
pipette  25  c.c.  of  the  zinc  solution  into  a  400  c.c.,  beaker. 
Dilute  somewhat  and  make  faintly  alkaline  with  ammonia, 
bring  to  a  faintly  acid  condition  with  hydrochloric  acid 
and  then  add  3  c.c.  excess  of  the  concentrated  acid,  dilute 
to  a  total  volume  of  about  250  c.c.,  heat  to  80°  C.  and 
titrate  as  follows:   Pour  off  about  10  c.c.  of  the  zinc  solu- 
tion into  a  small  beaker  and  set  aside,  run  the  ferrocya- 
nide into  the  remainder  from  a  burette,  a  few  c.c.  at  a 
time,  until  the  solution  takes  on  a  slight  ash  gray  color, 
or  until  a  drop  of  the  solution  placed  in  contact  with  a 
drop  of  the  uranium  nitrate  solution  on  a  porcelain  plate 
turns  to  a  distinct  brownish  color. 

434.  Often  the  end  point  has  been  passed  by  quite  a 
little.     The  10  c.c.  of  zinc  solution  that  has  been  reserved 
is  now  added  and  the  titration  continued,  drop  by  drop, 
testing  a  drop  of  the  solution  carefully  on  the  porcelain 
plate  after  each  addition  of  ferrocyanide  solution.     Some 
little  time  is  required  for  the  test  drop  to  change  color,  so 
that  the  end  point  may  have  been  passed  slightly;    this 
may  be  corrected  for  by  making  a  memorandum  of  the 
burette  readings,  having  the  test  drops  arranged  in  regular 
order  and  taking  as  the  proper  reading  the  one  first  show- 
ing a  distinct  brownish  tinge.     Having  noted  the  number 
of  cubic  centimeters  ferrocyanide  required  for  the  titration 
of  the  standard   zinc  solution,   the  value  of   1   c.c.  may 
be  readily  calculated. 


274  THE   LEAD   AND   ZINC  PIGMENTS. 

435.  Titration  of  Sample.   One-half  gram  of  the  sample 
if  high  in  zinc,  or  1  gram  if  the  zinc  content  is  fairly  low, 
is  dissolved  in  a  covered  beaker  in  10  c.c.  of  hydrochloric 
acid  and  10  c.c.  of  water,  the  solution  diluted  somewhat, 
neutralized   with   ammonia   and   treated   exactly   as   de- 
scribed above  for  the  standard  zinc  solution,  care  being 
taken  to  titrate  to  exactly  the  same  depth  of  color  on  the 
porcelain  test  plate.     If  the  method  is  carefully  carried 
out,  the  procedure  being  uniformly  the  same  in  each  deter- 
mination, the  results  will  be  found  satisfactorily  accurate. 

436.  II.   Precipitation  of  Zinc  as  Carbonate.     The  alco- 
holic filtrate  from  the  lead  sulphate  method  of  estimating 
lead  is  heated  gently  until  practically  all  of  the  alcohol  has 
been  driven  off.     The  remaining  liquid  is  transferred  to  a 
porcelain  dish  provided  with  a  beaker  cover,  and  sodium 
carbonate  added  cautiously  until  the  liquid  is  alkaline, 
care  being  taken  that  no  loss  occurs  due  to  the  efferves- 
cence.    The  zinc  is  precipitated  as  a  basic  carbonate,  and 
the  solution  should  be  boiled  gently  for  a  few  minutes  in 
order  to  insure  complete  precipitation.    As  stated  above 
this  operation  should  be  conducted  in  a  porcelain  dish,  as 
the  boiling  akaline  solution  attacks  glass  to  a  consider- 
able  extent.      Allow    the    precipitate  to  subside,  decant 
through  a  filter,  and  boil  the  precipitate  three  times  with 
water,  decanting  each  time,  wash  thoroughly  with  boiling 
water,  dry  and  remove  the  precipitate  as  completely  as 
possible  from  the  filter  paper.     Saturate  the  paper  with 
a  strong  solution  of  ammonium  nitrate,  dry  again  and 
ignite  the  paper.     The  ammonium  nitrate  serves  to  oxidize 
any  of  the  zinc  that  is  reduced  to  the   metallic  state    by 
the  carbon  of  the  filter  paper  and  which  would  otherwise 
be  lost  by  volatilization.     The  precipitate  is  then  intro- 
duced into  the  crucible  and  converted  by  ignition  into  the 
oxide  and  weighed  as  such. 


ANALYSIS   OF  THE  ZINC   PIGMENTS.  275 

437.  III.   Precipitation  of  the  Zinc  as  Phosphate.   The 
alcoholic  filtrate  from  the  lead  sulphate  after  the  removal 
of  the  alcohol  as  described  above  is  diluted  somewhat  if 
necessary,  about  20  to  30  grams  of  dry  ammonium  chloride 
added  and  made  alkaline  with  ammonia,  then  just  barely 
acid  with  acetic  acid  and  10  c.c.  of  a  cold  saturated  solu- 
tion of  microcosmic  salt  added.     The  solution  is  diluted 
to  a  bulk  of  about  200  c.c.,  heated  nearly  to  boiling  with 
vigorous  stirring,  in  order  to  make  the  precipitate  crystal- 
line.    Cool,  make  exactly  neutral  with  amrnonia,  allow  to 
stand  until  the  precipitation  is  complete,  filter  on  to  a 
weighed  Gooch  crucible,  washing  with  ammonium  nitrate 
solution,  ignite,  and  weigh  as  zinc  pyrophosphate. 

438.  Combined  Sulphuric  Acid.     Dissolve  0.5  gram  to 
1  gram  of  the  pigment,  according  to  the  amount  of  sul- 
phates present,  in 

Water,  25  c.c. 

Ammonia,  10  c.c. 

Hydrochloric  acid,  a  slight  excess. 

439.  Dilute  to  200  c.c.  and  add  a  disk  of  aluminum  foil, 
which  should  about  cover  the  bottom  of  the  beaker.     Boil 
gently  until  the  lead  is  precipitated,  holding  the  disk  if 
necessary  to  the  bottom  of  the  beaker  with  a  glass  rod. 
The  completion  of  precipitation  is  shown   by   the  lead 
ceasing  to  coat  or  cling  to  the  aluminum.     Decant  through 
a  filter,  pressing  the  lead  sponge  into  a  cake  and  washing 
thoroughly  to  free  from  solution. 

440.  Add  to  the  filtrate  a  few  drops  of  bromine  water, 
boil  and  precipitate  with  barium  chloride  in  the  usual 
manner  for  sulphates.     In  order  to  avoid  a  possible  reduc- 
tion of  a  portion  of  the  barium  sulphate  in  the  pores  of  the 
filter  paper  during  its  incineration,  the  precipitate  may  be 
filtered  directly  on  to  a  Gooch  crucible,  which  after  being 


276  THE    LEAD   AND   ZINC   PIGMENTS. 

weighed  has  a  disk  of  ashless  filter  paper  placed  on  top  of 
the  customary  asbestos  felt.  This  will  effectually  prevent 
any  of  the  precipitate  from  burrowing  through  the  filter. 
The  ignition  of  the  precipitate  in  the  presence  of  the  small 
disk  of  filter  paper  will  cause  no  appreciable  reduction  to 
sulphide. 

441.  Calculations.   The  amount  of  zinc  present  as  sul- 
phate of  zinc  is  deducted  from  the  total  zinc  and  the 
remainder  calculated  to  zinc  oxide.     The  sulphuric  acid 
combined  with  the  zinc  is  deducted  from  the  total  combined 
sulphuric  acid  and  the  remainder  calculated  to  lead  sul- 
phate.    Any  excess  of  lead  over  that  required  to  combine 
with  the  sulphuric  acid  is  calculated  to  lead  oxide.     Unless 
sublimed  lead  is  present  there  will  be  little  or  no  lead 
oxide. 

442.  Estimation  of  Arsenic  and  Antimony  in  Zinc  Leads. 
Weigh   2   grams  of  the  sample  into  a  200-c.c.  digestion 
flask.     Add  7  grams   of  potassium   bisulphate,  0.5  gram 
of  tartaric  acid,  and  10  c.c.  of  concentrated  sulphuric  acid. 
Digest  carefully  at  first,  but  finally  with  the  full  power  of 
a  Bunsen  burner  until  a  clear  mass  remains,  containing  but 
little  free  sulphuric  acid.     Cool,  spreading  the  melt  around 
on  the  sides  of  the  flask.     And  50  c.c.  of  water,  10  c.c.  of 
strong   hydrochloric   acid,    and   digest   for   about   twenty 
minutes  without  boiling. 

443.  Cool  thoroughly  under  the  tap,  and  filter  off  the 
separated    lead    sulphate.     Dilute    the    filtrate    to    about 
300  c.c.  with  hot  water,  maintain  the  liquid  warm,  and 
pass  in  hydrogen  sulphide  for  about  fifteen  minutes  or 
until    precipitation    is    complete.     Filter,    washing    with 
hydrogen  sulphide  water.     Digest  filter  and  contents  in  a 
rather  small  amount  of  yellow  ammonium  sulphide.     Filter 
on  suction  cone,  washing  with  as  small  a  quantity  of  water 
as  possible. 


ANALYSIS   OF  THE  ZINC  PIGMENTS.  277 

444.  Digest    the    filtrate   with   3   grams   of   potassium 
bisulphate  and  10  c.c.  of  strong  sulphuric  acid  over  a  free 
flame  until  all  of  the  free  sulphur  and  the  larger  portion  of 
free  acid  are  expelled.     Cool,  spreading  the  melt  around  on 
the  sides  of  the  flask  as  before.     Add  25  c.c.  of  water  and 
10  c.c.  of  strong  hydrochloric  acid,  and  warm  to  effect 
complete  solution.     Cool  under  the  tap,   add  40  c.c.   of 
strong  hydrochloric  acid,  and  pass  in  hydrogen  sulphide 
until  complete  precipitation  of  the  arsenic   takes  place, 
15  to  30  minutes.     The  antimony  remains  in  solution. 

445.  Filter  off  the  precipitated  arsenious  sulphide  on  to 
a  weighed  Gooch  crucible,  washing  with  a  mixture  pf  two 
volumes    of   hydrochloric    arid    and    one   of   water.     The 
filtrate  is  reserved  at  this  point  for  the  estimation  of  anti- 
mony.    The  precipitate  is  next  washed  with  alcohol,  the 
crucible  and  contents  placed  in  a  small  beaker,  the  cruci- 
ble nearly  filled  with  carbon  bisulphide,  and  the  contents 
allowed    to    digest    at    ordinary    temperature    for    about 
twenty  minutes  in  order  to  dissolve  the  free  sulphur.     The 
carbon   bisulphide   is   removed    by   suction,    the   crucible 
dried    in    the    steam   oven,    cooled,    and    the   precipitate 
weighed  as  arsenious  sulphide  and  calculated  to  arsenious 
oxide. 

Weight  arsenious  sulphide  X  0.8043  =  weight  arsenious 
oxide. 

446.  Instead  of  weighing  as  the  sulphide,  the  arsenic 
may  be  estimated  volumetrically  as  follows:  Wash  out  the 
hydrochloric  acid  from  the  sulphide  precipitate  with  hydro- 
gen sulphide  water.     Digest  filter  and  contents  in  a  little 
warm  ammonium  sulphide,  filter  on  a  suction  cone,  wash- 
ing  with    a   little    dilutea  mmonium    sulphide   solution. 
Place  the  filtrate  in  digestion  flask,  add  2  to  3  grams  of 
potassium  bisulphate  and  5  c.c.  of  strong  sulphuric  acid. 
Evaporate,  boiling  to  a  small  bulk,  and  then  manipulate 


278  THE  LEAD  AND   ZINC  PIGMENTS. 

the  flask  over  a  free  flame  until  the  sulphur  is  entirely 
expelled  and  most  of  the  free  acid  also.  Take  up,  after 
cooling,  by  warming  with  50  c.c.  of  water,  and  then  boil 
sufficiently  to  expel  any  possible  sulphur  dioxide.  Now 
drop  in  a  bit  of  litmus  paper  as  an  indicator,  and  then  add 
ammonia  until  the  solution  is  slightly  alkaline.  Again 
slightly  acidify  with  hydrochloric  acid  and  cool  to  room 
temperature.  Finally,  add  3  to  4  grams  of  sodium  acid 
carbonate  and  a  little  starch  liquor  and  titrate  with 
standard  iodine  solution.  Pay  no  attention  to  a  slight 
discoloration  toward  the  end,  but  proceed  slowly  until  a 
single  drop  of  the  iodine  produces  a  strong  permanent  blue 
color. 

447.  Preparation  of  Iodine  Solution.   The  iodine  solu- 
tion  may  be  prepared  by  dissolving  about  11  grams  of 
iodine  in  a  little  water  with  the   addition  of  about  20 
grams  of  potassium  iodide  and  diluting  to  1  liter.     Stand- 
ardize with  arsenious  oxide.     Dissolve  about  0.150  gram 
in  5  c.c.   of  strong  hydrochloric  acid  by  warming  very 
gently,    dilute    and    neutralize    as   described    above,    and 
finally  titrate  with  the  iodine  solution.     One  c.c  of  the 
latter  will  equal  about  0.003  gram  of  arsenic. 

448.  Antimony.    Very   nearly    neutralize     the    filtrate 
reserved  for  the  antimony  estimation  with  hydrochloric 
acid,  dilute  with  double  its  volume  of  hot  water,  and  pass 
in  hydrogen  sulphide  until  all  of  the  antimony  is  precipi- 
tated.    Filter,    washing    with    hydrogen  sulphide    water. 
Digest  filter  and  contents  in  a  little  ammonium  sulphide, 
filter  on  suction  cone  and  wash  with  dilute  ammonium 
sulphide.     Place  the  filtrate  in  the  digestion  flask  and 
add  about  3  to  4  grams  of  (pure)  potassium  bisulphate  and 
10  c.c.  of  strong  sulphuric  acid.     Boil  as  previously  de- 
scribed to  expel  first  the  water,  then  all  the  free  sulphur, 
and  finally  most  of  the  free  acid. 


ANALYSIS   OF  THE   ZINC  PIGMENTS.  279 

449.  Cool,  add  50  c.c.  of  water  and  10  c.c.  of  strong 
hydrochloric  acid.     Heat  to  effect  solution,  and  then  boil 
for  a  few  minutes  to  expel  any  possible  sulphur  dioxide. 
Finally,   add    10   c.c.   more  of  strong  hydrochloric   acid, 
cool  under  the  tap,  dilute  to  about  200  c.c.  with  cold  water 
and  titrate  with  a  standard  solution  of  potassium  perman- 
ganate.    The  solution  ordinarily  used  for  iron  titrations 
will  answer.     The  oxalic  acid  value  of  the  permanganate 
multiplied  by  0.9532  will  give  the  antimony  value. 

450.  Methods  of  Determining  Small  Amounts  of  Arsenic 
and  Antimony  in  Use  at  Canon  City,  Colorado. 

451.  Method  I.    Take  two  or  three  grams  of  pigment  and 
dissolve  in  10  c.c.  nitric  acid  and  10  c.c.  sulphuric  *ac  id. 
Heat  to  expel  the  nitric  acid  and  evaporate  to  sulphuric 
fumes.     The  advantage  of  the  nitric  acid  is  to  oxidize  the 
arsenic  present  and  thereby  avoid  any  loss  of  arsenious  acid 
by  volatilization.     Allow  to  cool  and  dilute  with  cold  water, 
add  about  50  per  cent  of  the  volume  of  alcohol  to  insure 
complete  precipitation  of  all  lead  as  lead  sulphate.     Filter 
and  wash,  boil  filtrate  to  expel  alcohol,  and  add  about  ten 
to  fifteen  cubic  centimeters  hydrochloric  acid.     Precipitate 
the  warm  solution  with  hydrogen  sulphide.     Filter  and 
wash  with  dilute  hydrogen  sulphide  water.     All  arsenic, 
antimony,  and  copper  are  on  the  filter  as  sulphides.     Test 
filtrate  with  hydrogen  sulphide  as  a  check  on  precipitation. 

452.  Dissolve  the  sulphides  in  caustic  potash  solution, 
then  bring  to  a  boil  and  pass  hydrogen  sulphide  into  warm 
solution  as  before.     Filter  and   test  filtrate.     Wash  with 
dilute  ammonium  sulphide  solution.     All  arsenic  and  anti- 
mony are  in  filtrate  and  any  copper  present  is  on  the  filter. 
If  any  copper  is  present,  dissolve  and  titrate  by  the  iodide 
method. 

453.  Make  filtrate  acid  with  hydrochloric  acid  and  add 
about  10  c.c.  excess  and  pass  in  hydrogen  sulphide  gas  as 


280  THE   LEAD   AND    ZINC  PIGMENTS. 

before.  Filter  off  the  sulphides  of  arsenic  and  antimony 
and  wash  with  hydrogen  sulphide  water.  Dissolve  these 
sulphides  in  about  10  c.c.  aqua-regia,  then  dilute  with 
water  and  make  alkaline  with  ammonia,  adding  about  25  c.c. 
excess.  Then  add  from  one  to  two  grams  tartaric  acid 
and  10  to  15  c.c.  magnesia  mixture.  Allow  to  stand  over 
night.  All  the  arsenic  is  precipitated  as  ammonium  mag- 
nesium arsenate.  Antimony  remains  in  solution,  being 
held  there  by  the  tartaric  acid  present.  Filter  off  the 
ammonium  magnesium  arsenate,  washing  with  cold  water 
containing  a  little  ammonia,  then  dry,  ignite,  and  weigh  as 
magnesium  pyroarsenate. 

454.  Acidify  the  filtrate  with  hydrochloric  acid  and  pre- 
cipitate the  antimony  with  hydrogen  sulphide  as  before; 
filter  and  wash  with  hydrogen  sulphide  water.     Separate 
the  antimony  sulphide  from  the  filter  paper  and  dissolve 
the   adhering  particles  with  ammonium  sulphide,   trans- 
ferring to  a  beaker.     Wash  with  ammonia  and  evaporate 
to  dry  ness  on  water  bath.     Carefully  add  a  few  drops  of 
nitric  acid  and  then  1  to  2  c.c.  of  fuming  nitric  acid  to  oxi- 
dize the  antimony.     Then  evaporate  to  small  bulk  for 
crucible,  and  heat  to  dryness  on  water  bath,  then  ignite  at 
low  red  heat  to  constant  weight.    Weigh  as  lead  sulphate. 

455.  Method  II.     Treat  ten  grams  pigment  in  No.  3-A 
casserole  with  about  ten  grams  potassium  bisulphate,  10  c.c. 
nitric  acid,  15  c.c.   sulphuric  acid,   and   about  0.5  gram 
tartaric  acid.     Run  to  strong  fumes;  continue  heating  until 
all  the  carbon  is  destroyed  and  the  solution  is  clear.     Cool, 
dilute,  and  boil  until  soluble  sulphates  are  in  solution.    Cool, 
filter,  and  wash  thoroughly.     Add  tartaric  acid  and  pass 
hydrogen  sulphide  gas.     Filter  off  arsenic  and  antimony 
sulphides.     Dissolve   precipitate   in   potassium   hydroxide 
solution  and  filter.     Pour  filtrate  into  solution  of  hydro- 
chloric acid   (2  to  1).     Pass  hydrogen  sulphide  gas  and 


ANALYSIS   OF  THE   ZINC  PIGMENTS.  281 

filter  off  As2S3  on  a  weighed  Gooch  crucible.     Wash  with 
alcohol  and  carbon  bisulphide  to  remove  sulphur. 

456.  Neturalize  filtrate  until  Sb2S3  begins  to  precipitate. 
Dilute  with  equal  volume  of  water,  pass  hydrogen  sulphide 
gas,  and  filter  off  precipitate,  Sb2S3,  on  a  weighed  Gooch 
crucible.  Wash  with  alcohol  and  carbon  bisulphide  to 
remove  sulphur.  Dry  and  weigh. 


CHAPTER  XXVII. 

ANALYSIS  OF  WHITE  LEAD  AND  PAINTS  IN  OIL. 

457.  Securing  a  Fair  Sample.     There  are  probably  more 
disagreements  and  differences  between  chemists  engaged 
in  paint  analysis  in  the  resulting  analyses  obtained  than  in 
any  other  field  requiring  the  services  of  trained  analytical 
chemists.     The  writer  has  seen  the  results  obtained  by 
taking  a  gallon  of  a  mixed  paint  of  one  of  the  leading 
brands  on  the  market  and  dividing  it  into  quarts  and  send- 
ing the  four  cans  to  different  chemists  who  made  a  specialty 
of   paint   analysis.      The   four   analyses    bore   very   little 
observable  connection  with  the  formula  by  which  the  paint 
was  made  or,  in  fact,  with  each  other.     These  differences 
could  have  arisen  from  only  the  following  causes : 

1.  The  paint  not  being  compounded  strictly  according  to 
formula. 

2.  Chemical  changes  and  loss  of  some  of  the  volatile 
constituents  in  mixing  and  grinding. 

3.  Not  securing  a  fair  sample  for  analysis. 

4.  Inaccurate  methods  of  analysis. 

458.  Variations  from  Formula.     Where  paints  are  made 
in  large  quantities,  each  mix  representing  100  gallons  or 
more,  it  is  a  very  easy  matter  for  the  man  who  does  the 
weighing  or  measuring  to  make  a  mistake.    This  is  especially 
true  of  the  liquid  constituents,  part  of  which  are  added 
before  the  mix  is  run  through  the  mill  and  the  remainder 
in  the  thinning  tank.     The  keeping  in  mind  the  number  of 
gallons  of  linseed  oil,  volatile  oil,  water,  etc.,  added  as  the 
workman  goes  back  and  forth  from  the  faucets  to  the  mixer 

282 


ANALYSIS   OF  WHITE  LEAD   AND  PAINTS  IN   OIL.     283 

or  thinning  tanks,  is  not  as  easy  as  it  may  seem  at  first 
glance,  especially  if  the  batch  is  a  large  one. 

459.  Chemical    Changes     in    Grinding.     The    chemical 
reactions  that  may  occur  between  different  pigments  when 
subjected  to  the  combined  action  of   heat  and  pressure 
have  not  been  given  the  consideration  they  should  by  the 
majority  of  paint  chemists.    The  day  of  water-cooled  paint 
mills  is  here,  but  there  are  many  paint  manufacturers  who 
are  yet  grinding  their  various  pigments  in  mills  that  are 
not  water-cooled,  and  most  of  them  have  but  little  idea 
how  hot  the  paste  will  get  toward  the  close  of  a  day's  run ; 
280°  and  even  300°  F.  are  not  unusual  temperatures/  The 
effect  of  high-temperature  grinding  on  white  lead  and  lin- 
seed oil  has  already  been  spoken  of  under  the  discussion  of 
properties  of  white  lead. 

460.  The  effect  of  pressure  is  well  illustrated  by  the 
following  experiment.     Using  considerable  pressure,  grind 
intimately  1  gram  of  lead  sulphate  with  3  grams  of  sodium 
carbonate  for  some  minutes  in  an  agate  mortar,  and  it  will 
be  found  that  practically  all  of  the  lead  sulphate  has  been 
converted  into  carbonate  and  the  sodium  carbonate  into 
sodium  sulphate.     Bleached  oil  carrying  traces  of  sulphuric 
acid  and  zinc  oxide  containing  zinc  sulphate  will  certainly 
react  with  white  lead  when  ground  under  pressure  at  a 
comparatively  high  temperature.     In  this  connection  the 
catalytic  action  of  sulphur  dioxide,  which  occurs  in  greater 
or  less  quantities  in  zinc  oxides  and  especially  in  leaded 
zincs,  should  not  be  overlooked,  especially  when  these  pig- 
ments are  used  in  the  manufacture  of  mixed  paints. 

461.  In  paint  factories  where  the  different  operations 
are  under  the  guidance  of  a  capable  chemist,  losses  arising 
from  evaporation  of  the  volatile  thinners  in  the  mixing 
tanks,  etc.,  should  not  occur,  but  there  is  many  a  mixed 
paint  that  when  sealed  in  the  can  does  not  contain  the 


284  THE  LEAD   AND   ZINC  PIGMENTS. 

same   percentage   of   volatile   thinners   as   was   originally 
added. 

462.  Obtaining  an  Average  Sample.   The  reason,   how- 
ever, for  the  majority  of  the  disagreements  between  paint 
chemists  lies  in  not  securing  an  average  sample  for  analy- 
sis, i.e.,  the  sample  taken  does  not  represent  the  average 
composition  of  the  paint  in  the  package  to  be  analyzed. 
This  is  especially  true  of  mixed  paints.     The  can  of  paint 
submitted    to   the  chemist    may    have    been  on  a  store 
shelf  for  some  months,   until  the  pigments  have  settled 
hard  in  the  bottom  of  the  can  and  the  task  of  breaking 
them  up  and  recombining  them  with  the  oil  portion  is  by 
no  means  an  easy  one.     Whenever  a  sample  is  received  in 
which  the  pigments  have  settled  out,  the  oil  portion  should 
be  poured  off  as  completely  as  possible,   the  remaining 
paste  entirely  removed  from  the  can  into  the  mixing  can, 
which   should   have   at   least   twice   the   capacity   of   the 
sample   can.     Using  a  very  stiff  spatula,   break   up   the 
paste  thoroughly  and  gradually  work  the  oil  portion  back 
into  the  paste.     The  first  addition  of  oil  should  be  small 
and    the   paste   worked   thoroughly   after   each   addition. 
When  the  oil  is  all  in,  the  paint  should  run  off  from  the 
spatula  smoothly  without  showing  any  evidence  of  lumps. 

463.  Having  reduced  the  paint  to  uniform  consistency, 
it  should  be  kept  tightly  covered  to  prevent  loss  of  the 
volatile  thinners  until  all  the  samples  necessary  for  analy- 
sis have  been  taken  out,  and  especial  care  should  be  taken 
to  stir  the  paint  thoroughly  each  time  before  taking  the 
samples,    as   the   heavier   pigments   tend   to   settle   more 
rapidly  than  those  having  a  lighter  specific  gravity. 

464.  Inaccurate  Methods  of  Analysis.   Inaccurate  meth- 
ods in  making  the  analysis   have   doubtless   had    consid- 
erable to  do  with    the   disagreements   above  mentioned. 
However,   much  progress  has   been  made  in  improving 


ANALYSIS   OF   WHITE   LEAD   AND   PAINTS  IN   OIL.     285 


methods  during  the  last  few  years,  so  that  this  considera- 
tion does  not  apply  as  seriously  as  formerly. 

465.  Extraction  of  the  Vehicle.   The  pigment  may  be 
freed  from  oil  in  the  following  type  of  ap- 
paratus,  although  the    Soxhlet   extractor 

may  be  used  if  desired.  A  folded  filter 
paper  is  inserted  in  a  suitable  sized  S.  &  S. 
thimble,  dried  in  the  oven  for  a  few  min- 
utes, cooled  in  the  desiccator,  and  weighed. 
A  weighed  amount  of  the  sample  re- 
duced to  a  uniform  consistency  is  intro- 
duced into  the  thimble;  12  to  18  grams 
will  furnish  an  ample  amount  of  pigment 
for  analysis.  Ether  can  be  used  to  advan- 
tage as  the  volatile  solvent  when  the 
paint  contains  little  or  no  water,  but  for 
paints  containing  a  considerable  amount 
of  water,  acetone  will  be  found  superior  to 
ether  as  a  solvent.  In  order  to  secure  as 
complete  a  removal  of  the  vehicle  as  pos- 
sible, the  extraction  should  continue  for 
24  hours.  In  order  to  reduce  the  danger 
from  fire,  the  extractor  can  be  heated  with 
advantage  by  means  of  an  electrically 
heated  water-bath.  After  the  extraction 
is  complete,  the  thimble  and  contents  are 
dried  for  two  to  three  hours  in  the  steam 
oven,  cooled  in  the  dessicator,  and  weighed. 
The  loss  in  weight  suffered  by  the  paint 
represents  the  amount  of  vehicle.  The 
pigment  is  reduced  to  a  uniformly  fine 
powder  and  placed  in  a  small  tightly 
stoppered  sample  bottle  until  required  for  analysis. 

466.  Removal  of  Vehicle  for  Examination.   A  conven- 


FIG.  84. 
EXTRACTION 
APPARATUS. 


286  THE   LEAD   AND   ZINC  PIGMENTS. 

lent  method  of  obtaining  sufficient  vehicle  from  a  paint 
for  the  determination  of  the  volatile  oils,  the  quality  of 
the  linseed  oil,  etc.,  is  to  fill  a  tall  cylinder  with  such  of 
the  sample  as  is  not  needed  for  the  water  estimation  (100 
to  150  grams)  and  for  obtaining  the  free  pigment,  corking 
it  tightly  and  placing  it  in  a  tall  copper  can  filled  with 
water  heated  to  about  70°  C.  By  reducing  the  viscosity 
of  the  oil  in  this  manner  the  pigment  will  settle  quite 
rapidly,  and  in  24  hours,  if  the  temperature  is  maintained 
at  70°  C.,  sufficient  oil  may  be  siphoned  off  with  the  aid  of 
the  suction  pump.  For  the  removal  of  volatile  oils  by 
distillation  with  steam  at  130°  C.  and  an  examination  of 
the  linseed  oil  remaining  behind,  as  well  as  for  the  identi- 
fication and  separation  of  the  volatile  oils  from  each  other, 
the  reader  is  referred  to  the  "  Analysis  of  Mixed  Paints, 
Color  Pigments,  and  Varnishes/'  published  by  the  writer. 

467.  Use   of   Centrifuge.     By  far  the  most   convenient 
method  of  obtaining  sufficient  vehicle  for  examination  is 
by  centrifuging  the  paint.     In  the  average  laboratory  an 
electric  centrifuge  is  the  most  convenient  type.     The  cyl- 
inders used  may  be  of  glass,  but  preferably  of  aluminum, 
as  the  pressure  on  the  ends  will  often  exceed  50  pounds 
per  square  inch  when  the  centrifuge  is  in  motion.     The 
bottoms    of    the    cylinders    should    be    removable,   being 
screwed   on  to   the   cylinder.     This   permits   of  the  easy 
removal  of  the  precipitated  paint  and  the  rapid  cleaning 
of  the  cylinders. 

468.  It  is  necessary  that  the  cylinders  opposite  each 
other  be  evenly  balanced,  and  it  is  always  advisable  to 
balance  up  the  cylinders  on  the  scales  before  placing  them 
in  the  centrifuge.     The  cylinders  should  be  tightly  corked 
to  prevent  loss  by  evaporation  of  the  volatile  thinners, 
and  live  steam  admitted  into  the  centrifuge  chamber  suffi- 
cient to  heat  the  contents  of  the  tubes  to  about  70°  C. 


ANALYSIS  OF  WHITE  LEAD   AND   PAINTS  IN  OIL.      287 

In  the  majority  of  cases  the  pigment  will  be  thrown  out 
rapidly  and  cleanly  and,  by  using  a  number  of  cylinders, 
an  ample  amount  of  the  oils  may  be  easily  obtained. 

469.  In  the  factory  laboratory,  where  steam  pressure  is 
always  available,  an  ordinary  steam  centrifuge  such  as  is 
used   for  the  ordinary  Babcock   butter-fat  test  is  more 
convenient  than  the  electric  machine,  as  the  steam  leak- 
age into  the  upper  chambers   is  sufficient   to   keep    the 
tubes  warm  enough  to  insure  the  rapid  precipitation  of  the 
pigment. 

470.  Use  of  Volatile  Petroleum  Thinners.     A  word  may 
be  said  in  connection  with  the  increased  use  of  -volatile 
petroleum  products  as  paint  thinners.     In  discussing  this 
subject  a  prominent  paint  chemist  states  the  problem  as 
follows : 

"  The  rapid  depletion  of  our  turpentine  forests  and  the 
rapid  advance  in  the  price  of  turpentine  has  brought 
prominently  before  every  paint  and  varnish  manufac- 
turer the  absolute  necessity  for  some  volatile  solvent 
capable  of  replacing  entirely  or  in  part  the  turpentine  he 
used."  The  answer  to  this  problem  has  been,  naturally, 
the  flooding  of  the  market  with  an  innumerable  number 
of  substitutes  of  uncertain  merit.  Some  of  the  smaller 
paint  companies,  and  especially  those  making  paint  for 
"  a  price,"  have  adopted  some  of  these  substitutes  without 
a  careful  investigation  of  their  merits.  On  the  other  hand, 
some  of  the  larger  and  more  completely  equipped  com- 
panies have  devoted  considerable  study  to  the  question 
of  turpentine  substitutes,  first  endeavoring  to  ascertain 
the  exact  function  of  the  turpentine  in  the  paint  and  then 
seeking  to  prepare  an  article  that  would  have  the  same 
essential  properties  and  at  the  same  time  be  free  from 
objectionable  characteristics. 

471.  According  to  the  views  of  leading  chemists,  the 


288  THE   LEAD   AND   ZINC  PIGMENTS. 

purpose  of  the  turpentine  in  the  paint  is  to  increase  the 
penetration  of  the  oil  and  pigments  into  the  wood  and 
under  coats  of  paints;  to  produce  a  "  flat  "  or  "  semi-flat  " 
surface,  permitting  a  closer  union  with  the  succeeding 
coat,  or  for  appearance  as  in  the  case  of  paints  intended 
for  inside  use;  to  render  the  paint  more  fluid  without  the  use 
of  an  excessive  amount  of  oil;  to  increase  the  speed  of  the 
drying  of  the  paint  both  by  evaporation  and  by  oxidation; 
and  finally,  to  act  as  a  bleaching  agent  on  the  oil,  rendering 
the  paint  whiter;  this,  however,  is  not  as  essential  as  the 
other  functions  of  the  turpentine.  Naturally  chemists 
turned  to  the  various  petroleum  products  in  their  search 
for  the  desired  substitute,  and  as  a  result  of  their  studies 
a  number  of  companies  are  using  a  product  which  does  not 
behave  like  any  of  the  petroleum  distillates  with  which 
the  chemist  is  ordinarily  familiar. 

472.  Characteristics.     This  product  is  used  under  various 
trade  names  and  differs  slightly  in  composition  according 
to  the  petroleum  or  petroleums  from  which  it  is  derived, 
i.e.,  whether  of  Texas,  Russian,  or  of  some  other  origin. 
It  is  prepared  so  that  it  has  a  flash  point  slightly  above 
that  of  turpentine,  and  hence  as  a  fire  risk  it  is  as  safe 
as  turpentine,  which  is  in  marked    contradistinction   to 
benzine.     It  evaporates  cleanly,  and  at  a  rate  about  or 
slightly   slower   than    ordinary    turpentine.     In    securing 
penetration  of  the  paint  it  is  fully  equal  to  turpentine  and 
is  free  from  objectionable  odors.     In  order  to  overcome 
the  deficiency  of  not  assisting  the  paint  in  drying  by 
oxidation  and  the  lack  of  bleaching  action  on  the  linseed 
oil,  several  paint  manufacturers  add  a  sufficient  percentage 
of  spirits  of  turpentine  to  supply  these  desired  qualities. 

473 .  Reporting  Results.  The  chemist  in  making  an  analysis 
of  paints  should  be  very  careful  in  stating  the  composition 
of  the  volatile  oils  used  in  the  vehicle,  and  not  confound 


ANALYSIS  OF  WHITE    LEAD  AND   PAINTS   IN   OIL.      289 

these  turpentine  substitutes  with  ordinary  benzine,  which 
costs  considerably  less  than  half  as  much  and  is  danger- 
ous to  use  on  account  of  the  fire  risk  and  is  too  volatile 
to  be  accepted  as  a  proper  turpentine  substitute.  The 
analysis  of  these  substitutes  when  once  incorporated  into 
the  paint  is  somewhat  difficult,  but  with  care  may  be 
obtained  by  distillation  as  above  mentioned.  Having 
secured  the  volatile  distillate  and  having  freed  it  from  all 
traces  of  water  it  may  be  redistilled,  using  a  small  distilling 
flask  and  carefully  noting  the  temperatures  at  which  the 
product  passes  over.  The  substitutes  of  recognized  merit 
distil  usually  between  150°  and  200°  C.  Any  benzine 
present  will  pass  over  below  150°  C.,  and  kerosene  mostly 
above  200°  C.  If  the  latter  is  present,  however,  a  large 
portion  will  not  be  volatile  in  the  steam  distillation  and 
will  remain  in  the  linseed  oil,  being  readily  detected  in  the 
latter  by  pouring  six  drops  in  a  few  cubic  centimeters  of 
an  alcoholic  solution  of  potash,  boiling  gently  for  two 
minutes  and  pouring  into  a  little  distilled  water,  a  decided 
cloudiness  indicating  the  presence  of  unsaponifiable  petro- 
leum oils. 


CHAPTER  XXVIII. 

ESTIMATION  OF  WATER  IN  WHITE  LEADS  AND  PAINTS. 

474.  Occurrence.   A   fraction   of   1    per   cent   of   water 
may  occur  normally  in  the  vehicle.     A  small  percentage, 
1  to  3  per  cent,  may  be  incorporated  into  the  paint  by  the 
manufacturer  under  the  belief  that  it  secures  better  pene- 
tration when  applied  to  surfaces  that  are  slightly  damp, 
and  also  that  it  will  prevent  the  pigment  from  settling 
hard  in  the  can.     Oftentimes,  however,  large  quantities 
are  introduced  for  the  purpose  of  cheapening  the  product. 
The  water  may  be  added  to  the  paint  and  prevented  from 
separating  out,  by  forming  an  emulsion  with  the  oil  with 
the  aid  of  an  alkali,  or  by  grinding  it  into  the  pigment, 
using  an  adhesive  such  as  glue  or  casein.     In  the  first  case 
the  nature  of  the  ash  left  on  burning  some  of  the  sepa- 
rated vehicle  will  indicate  whether  an  alkali  has  been  used 
or  not.     In  the  second  case  the  vehicle  will  yield  less  than 
one  per  cent  of  water  when  distilled  with  a  dry,  inert  sub- 
stance such  as  sublimed  lead,  as  the  water  remains  with 
the  pigment. 

475.  Detection.   Water  may  be  tested  for  qualitatively 
in  light-colored  paints,  by  rubbing  with  a  little  eosin  on  a 
glass  plate.     If  water  is  present  the  paint  will  take  on  a 
strong  pink  color,  otherwise  the  color  will  remain  prac- 
tically   unchanged.     If    the    paint    contains    considerable 
coloring  material,  rendering  the  eosin  test  inapplicable, 
a  weighed  strip  of  gelatirie  may  be  immersed  in  the  paint 
for  several  hours.     If  water  is  present  the  gelatine  will 
soften  and  increase  in  weight,  the  adhering  paint  being 
removed  by  the  use  of  petroleum  ether  and  drying  for  a 

290 


WATER  IN   WHITE   LEADS   AND   PAINTS.  291 

minute  or  two  between  sheets  of  filter  paper.  An  immer- 
sion of  the  gelatine  for  18  to  24  hours  will  show  the  pres- 
ence of  water  in  a  paint  containing  as  little  as  2  per  cent. 
476.  Estimation.  Quantitatively,  the  water  may  be  esti- 
mated by  distillation,  using  a  retort,  the  neck  of  which 


FIG.  85.  — ESTIMATION  OP  WATER. 


forms  the  inner  tube  of  a  condenser,  the  outside  tube  being 
a  Welsbach  chimney.  One  hundred  grams  of  the  paint 
is  weighed  into  an  aluminum  beaker  and  mixed  with  a 
thoroughly  dried,  inert  pigment  like  silica  or  sublimed 


292  THE  LEAD   AND   ZINC  PIGMENTS. 

lead  until  it  ceases  to  be  pasty,  and  then  transferred  to  the 
retort,  which  is  heated  in  an  oil  bath,  the  water  being 
collected  in  a  graduate  calibrated  to  fifths  of  cubic  centi- 
meters. Toward  the  end  of  the  distillation,  the  tempera- 
ture of  the  contents  of  the  retort  being  raised  to  200°  C., 
a  very  slow  current  of  air  or  illuminating  gas  is  admitted 
to  the  retort  through  a  tube  passing  nearly  to  the  surface 
of  the  pigment.  This  will  carry  over  the  last  traces  of 
moisture. 

477.  It  is  advisable  to  pass  the  illuminating  gas  through 
a  wash-bottle  containing  sulphuric  acid,  which  not  only 
serves  to  remove  moisture,  but  acts  as  an  indicator  for 
the  rate  of  flowing  gas.     The  heating  should  be  continued 
for  at  least  two  hours  at  the  above  temperature  to  insure 
the  complete  removal  of  the  combined  water  from  the  basic 
carbonate  of  lead  which  may  be  present.     This  should  be 
deducted  from  the  total  amount  of  water  obtained,  by 
multiplying  the  basic  carbonate  present  by  2.3  per  cent, 
which  represents  the  average  per  cent  of  combined  water 
in  white  lead. 

478.  It    is    impossible    to   remove   the   water   by   this 
method,  without  decomposing  part  of  the  lead  hydrox- 
ide of  the  white  lead,  as  it  begins  to  lose  the  combined 
water  at  105°  to  120°  C.,  the  total  combined  water  being 
driven  off  at  150°  C.  for  6  hours  with  little  or  no  loss  of 
carbon  dioxide.     An  exposure  of  4  hours  at  a  temperature 
175  degrees  results  in  the  loss  of  all  the  water  and  a  slight 
amount  of  carbon  dioxide;  at  200°  degrees  an  exposure  of 
2  hours  is  sufficient  to  remove  all  of  the  combined  water 
and  about  one-quarter  to  one-third  of  the  carbon  dioxide. 

In  each  case  a  blank  should  be  run  in  order  to  ascertain 
that  the  inert  pigment  and  illuminating  gas  are  free  from 
condensible  moisture. 

The  author  believes  that  a  current  of  air  obtained  by 


WATER   IN   WHITE   LEADS  AND  PAINTS.  293 

the  use  of  an  aspirator  is  preferable  to  the  use  of  illumi- 
nating gas,  as  with  the  latter  there  is  the  possibility  of  the 
formation  of  water  from  the  hydrogen  of  the  illuminating 
gas  and  the  lead  oxide  present,  if  the  temperature  is  raised 
.too  high. 

479.  Estimation   of   Water   with  Amyl   Reagent.     This 
method,  worked  out  by  the  author  in  his  laboratory,  has 
given  excellent  results,  not  only  in  mixed  paints  but  also 
in   paste  and   semi-paste  goods.     The  determination   re- 
quires only  a  few  minutes  and  as  the  combined  water  of 
the  white  lead  is  not  driven  off,  there  is  no  correction  to 
be  applied. 

480.  Preparation  of  Amyl  Reagent.     The  components  of 
the  amyl  reagent  —  amyl  acetate  and  amyl  valerianate  — 
should  be  as  pure  as  possible,  and  unless  of  specified  purity 
an  inferior  grade  is  apt  to  be  obtained.     Fritsche  Bros., 
New   York   City,  have   furnished    the   most   satisfactory 
article  the  author  has  been  able  to  secure.     The  amyl 
acetate  and  valerianate  should  be  washed,  before  mixing, 
with  at  least  two  changes  of  pure  distilled  water  at  room 
temperature.     This  can  readily  be  accomplished  in  a  large 
separatory  funnel.     Washing  with  water  will  remove  prac- 
tically all  of  the  impurities  and  such  as  may  remain  will 
be  saturated   at  that  temperature.     The  reagent  is  pre- 
pared by  mixing  5  parts  of  amyl  acetate  with  1  part  of 
amyl  valerianate. 

481.  Determination.   About  100  grams  of  the  thoroughly 
stirred  sample  of  paint  are  weighed  into  a  flat-bottomed, 
200-250-c.c.,  side-necked  distilling  flask.    Add  75  c.c.  of 
the  amyl  reagent  and  with  a  gentle  rotary  motion  secure 
a  thorough  mixing  of  the  contents  of  the  flask.     Connect 
with  an  upright  condenser  and  distill  over  about  60  c.c.  of 
the  reagent  into  a  cylinder  graduated  into  tenths  of  cubic 
centimeters.     When  the  larger  portion  of  water  has  passed 


294 


THE   LEAD   AND   ZINC  PIGMENTS. 


over,  the  upper  portion  of  the  flask  should  be  warmed 
gently  with  the  naked  flame,  in  order  to  expel  the  small 
portion  of  moisture  that  will  have  collected  on  the  sides 
of  the  flask.  The  distillation  should  then  be  continued 
until  the  requisite  amount  of  reagent  has  distilled  over. 
The  percentage  of  water  can  then  be  easily  read  off  from 
the  graduated  cylinder  and  the  contents  of  the  distilling 
flask  will  be  sufficiently  liquid  to  insure  easy  removal. 
With  paints  high  in  volatile  oils  the  volume  of  the  dis- 
tillate should  be  increased  to  at  least  75  c.c. 

482.  Practical  Example.  The  following  determination 
with  a  paint  of  known  water  content  indicates  the  satis- 
factory nature  and  accuracy  of  this  method. 

White  lead 115  grams 

Linseed  oil 40  grams 

Turpentine 10  grams 

Water 6  grams 

were  thoroughly  mixed,  introduced  into  a  side-necked  dis- 
tilling flask,  75  c.c.  of  the  prepared  amyl  reagent  added 
and  the  mixture  agitated  until  of  uniform  consistency. 
The  following  distillation  figures  were  obtained: 


Temperature. 

Water. 

Amyl  reagent  and 
turpentine. 

92°-110°C. 
110°-125°C. 
125°-140°  C. 
140°-145°  C. 

5.5  c.c. 
0.9  c.c. 
0.0  c.c. 
0.0  c.c. 

16  c.c. 
13  c.c. 
18  c.c. 
14  c.c. 

6.4  c.c. 

61  c.c. 

The  same  mixture  without  the  addition  of  water  gave 
0.3  c.c.  of  water  when  run  as  a  blank. 

Theoretical  percentage  of  added  water 3 . 51 

Percentage  of  water  obtained  (corrected ) . .  .  3 . 56 


CHAPTER  XXIX. 

QUALITATIVE   ANALYSIS    OF    COMBINATION   WHITE    LEADS 
AND  PASTES. 

483.  Classification.  The  various  pigments  to  be  found  in 
"  combination  leads,"  base  whites  and  the  various  mixed 
paints  may  be  divided  into  two  classes,  the  so-called  active 
pigments  and  the  inert  pigments. 

The  active  pigments  comprise 

White  lead. 

Sublimed  white  lead. 

Zinc  oxide. 

Zinc  lead  white. 

Leaded  zincs  and 

Lithopone. 
The  inert  pigments  comprise 

Barium  sulphate  (Barytes,  Blanc  fixe). 

Barium  carbonate. 

Calcium    carbonate    (Whiting,    Paris    white,    White 
mineral  primer). 

Calcium  sulphate  (Gypsum,  Terra  alba). 

China  clay  (Kaolin). 

Asbestine  (Magnesium  silicate). 

Silica  (Silex). 

The  properties  of  the  various  active  pigments  have  been 
discussed  under  their  methods  of  manufacture  and  need 
not  be  taken  up  here. 

484.  Inert  Pigments.  The  inert  pigments  have  widely 
different  properties  not  only  from  a  chemical  standpoint 
but  from  a  physical   standpoint  as  well,  and  while  two 
pigments  may  have  the  same  chemical  composition  they 

295 


296  THE  LEAD  AND   ZINC  PIGMENTS. 

may  differ  greatly  in  physical  properties,  producing  entirely 
different  results  when  used  in  paints.  Hence  it  is  practi- 
cally impossible  to  judge  service  values  of  paints  contain- 
ing inert  pigments  from  the  chemical  analysis.  Chemical 
analysis,  however,  in  conjunction  with  a  careful  micro- 
scopic examination,  especially  if  a  polarizing  microscope 
be  used,  may  give  some  idea  of  what  the  service  value 
should  be. 

485.  Barium  Sulphate    (Barytes,  Blanc  Fixe).     Barytes 
is  perhaps  the  most  extensively  used  of  the  inert  pigments. 
It  more  nearly  approximates  white  lead  in  specific  gravity 
and  oil-taking  capacity  than  any  of    the  others.     It  is 
absolutely  unaffected   by   acids,   alkalies   or  atmospheric 
influences    of    any    kind.     Its    hiding   power   or   opacity 
when  ground  in  oil  is  very  low,  and  hence  when  used  in 
any  considerable    percentage   in  a  mixed  paint    or  com- 
bination   lead  its  presence   is    indicated  by  the  reduced 
opacity  of  the  paint  film.     The  requisites  of  a  high  grade 
of    barytes    are    whiteness    and    fineness.     The    cheaper 
grades  of  barytes  have  a  yellowish  gray  color  and  are 
often  treated  with  sulphuric  acid  to  improve  the  color  by 
removing  the  iron.     A  considerable  portion  of  the  barytes 
on  the  market  is   "  blued/'  either  by  precipitating  the 
iron   sulphate    obtained  by  the  treatment  with  the  sul- 
phuric acid  as  Prussian  blue,  or  adding  the  Prussian  or 
ultramarine  blue  separately.     The  majority  of  paint  manu- 
facturers,   however,    prefer   to    blue    their    goods    them- 
selves, if  necessary,  during  the  process  of  manufacture. 
The  fineness  with  which  barytes  has  been  ground  can  be 
easily  determined  by  examination  under  the  microscope 
after  the  acid  soluble  pigments  have  been  dissolved  out. 

486.  Blanc    fixe   is    a   precipitated     barium    sulphate. 
Owing  to  its  more  amorphous  character  it  has  a  much 
greater  hiding  power  than  barytes.     Its  oil-taking  capacity 


QUALITATIVE  ANALYSIS  OF   LEADS   AND  PASTES.    297 

is  greater;  it  does  not  settle  in  a  paint  as  badly  as  barytes 
and  is  much  whiter;  its  cost,  however,  is  about  twice  as 
great.  It  is  largely  used  as  an  inert  base  for  organic 
lakes. 

487.  Barium  Carbonate.    This  pigment  is  used  compar- 
atively little  in  the  United  States  a*  a  paint  pigment.     In 
physical  and  chemical  properties  it  much  resembles  white 
mineral  primer,  a  form  of  calcium  carbonate,  although  it 
does  not  require  as  much  oil  in  grinding.     Its  specific 
gravity  is  about  that  of  barytes.     It  dissolves  readily  in 
acetic,  nitric  and  hydrochloric  acids;  sulphuric  acid  con- 
verts it  slowly  into  insoluble  barium  sulphate.     In  the 
hundreds  of  mixed  paints  examined  by  the  writer  barium 
carbonate  was  found  to  be  present  in  only  one   paint, 
although    its   presence   in    certain    organic    lakes    is    not 
uncommon  in  a  precipitated  form. 

488.  Calcium  Carbonate,    Paris  White,  Whiting,  Alba 
Whiting,  White  Mineral  Primer. 

Under  the  heading  of  calcium  carbonate  we  have  three 
distinct  classes  of  pigments.    Those  obtained  from 

1.  English  cliffstone  or  similar  chalk  formations  such  as 
Paris  white,  gilders'  whiting  and  commercial  whiting. 

2.  Marble  or  a  crystalline  calcium  carbonate  such  as 
marble  dust,  white  mineral  primer,  etc. 

3.  Precipitated  calcium  carbonate  such  as  alba  whiting. 

489.  The  English  cliffstone  pigments  are  usually  put 
on  the  market  in  about  three  grades.    The  first  grade  is 
the  whitest  and  most  finely  ground  and  bolted  and  is  usually 
sold  under  some  such  name  as  Paris  white,  and  finds  its 
use  largely  in  first  quality  mixed  paints  and  combination 
leads.    The  second  grade  is  slightly  coarser  and  has  a 
slightly  grayish  tint  and  is  usually  sold  under  some  such 
name  as  gilders'  whiting.     It  is  also  usually  bolted,  and 
is  used  in  second  and  third  grade  paints.     The  third  grade 


298  THE  LEAD   AND   ZINC  PIGMENTS. 

is  inferior  in  color  and  fineness  to  the  other  two  grades. 
It  finds  its  chief  use  in  kalsomine;  although  it  is  used  in 
some  of  the  very  inferior  paints,  it  never  should  be,  owing 
to  the  fact  that  it  is  not  bolted,  and  therefore  contains 
some  relatively  large  particles.  It  is  usually  sold  as  com- 
mercial whiting. 

490.  The  various  forms  of  white  mineral  primer  are  of 
an  entirely  different  nature  physically  from  the  cliffstone 
products,  being  fragments  of  small  crystals.     They  have 
very  little  body  in  oil,  being  nearly  transparent.    They  are 
usually  whiter  than  Paris  white  and  possess  much  greater 
tooth,  but  are  not  much  used  in  mixed  paints  owing  to 
the  fact  that  they  settle  badly  in  the  can  and  have  very 
little  opacity.     They  find  their  chief  use  in  primers  and  in 
putty  for  making  it  work  shorter.     Being  of  a  crystalline 
nature  it  is  natural  that  they  require  less  oil  in  grinding 
than  Paris  white. 

Alba  whiting  and  other  precipitated  calcium  carbonate 
pigments  are  very  white,  but  being  very  light  and  fluffy 
require  an  enormous  amount  of  oil  in  grinding. 

While  it  is  not  an  easy  matter  to  distinguish  these 
different  products  in  a  paint,  yet  the  microscope  is  of  much 
value  in  determining  the  fineness  of  grinding. 

491.  Calcium  Sulphate  (Gypsum,  Terra  Alba).    This  pig- 
ment is  found  in  combination  white  leads  and  exterior 
white  paints  only  to  a  limited  extent.     Its  chief  use  seems 
to  be  in  certain  lines  of  railroad  paints  and  in  dipping  or 
implement  paints.     It  is  also  used  to  some  extent  as  a 
base  for  striking  certain  organic  lakes  upon,  notably  the 
para  reds.     The  writer,  despite  the  favorable  opinions  of 
many  eminent   paint   authorities,  does   not    believe  that 
calcium  sulphate,  or  gypsum,   as  it  is   more    commonly 
known,  is  adapted  for  use  in  exterior  paints  owing  to  its 
solubility  in  water,  it  being  soluble  about  one  part  in  five 


QUALITATIVE  ANALYSIS  OF   LEADS  AND   PASTES.     299 

hundred.  A  linseed  oil  paint  film  is  by  no  means  impervious 
to  moisture  and  the  continued  action  of  rains  and  storms 
cannot  be  otherwise  than  unfavorable,  as  the  solvent 
action  of  the  water  in  removing  a  portion  of  the  gypsum 
.renders  the  paint  film  more  porous  and  its  disintegration 
more  rapid. 

492.  Venetian  reds  often  contain  fifty  to  eighty  per  cent 
of  calcium  sulphate.     The  better  class  of  Venetian  reds  are 
composed  of  fifty  per  cent  of  ferric  oxide  and  fifty  per  cent 
of  calcium  sulphate.     This  calcium  sulphate  should  not  be 
confounded  with  the  forms  above  discussed,  as  it  has  been 
subjected  to  the  action  of  a  high  heat  and  is,  therefore, 
insoluble  in  water,  and  is  regarded  as  a  proper  constituent 
of  Venetian  reds. 

493.  Aluminum  Silicate  (China  clay,  Kaolin,  Tolanite). 
This  pigment  also  finds  but  little  use  in  combination  white 
leads  owing  to  its  low  specific  gravity.     It  is,  however,  used 
extensively  in  mixed  paints,  implement  paints,  and  as  an 
inert  base  for  striking  para  and  other  organic  reds  upon, 
especially  for  colors  which  are  used  in  dipping  paints.     Its 
functions  and  properties  are  very  similar  to  those  of  mag- 
nesium silicate,  it  being  essentially  a  suspender  for  prevent- 
ing settling  in  paints.     It  is  very  inert  in  its  action  with 
acids  and  alkalies.     Strong  hydrochloric  acid  with  con- 
tinued boiling  will  dissolve  a  very  slight  fraction  of  one  per 
cent,  hence  traces  of  aluminum  may  be  found  in  a  hydro- 
chloric acid  solution  of  a  paint  containing  aluminum  sili- 
cate.    Some  of  the  silicates  much  in  favor  with  the  paint 
trade  contain  a  considerable  percentage  of  what  is  appar- 
ently uncombined  silica.     In  mixed  paints  it  is  often  used 
with  magnesium  silicate.     Hence  a  microscopic  examina- 
tion is  usually  required  to  determine  whether  the  latter  is 
present  or  not.     It  yields  to  treatment  by  fusion  with 
sodium  carbonate  more  readily  than  magnesium  silicate. 


300  THE  LEAD   AND   ZINC  PIGMENTS. 

When  subjected  to  a  high  temperature  it  loses  eleven  to 
thirteen  per  cent  of  water  of  hydration. 

494.  Magnesium  Silicate  (Asbestine  pulp,  Talcose).    This 
pigment  is  sold  under  the  various  names  of  white  silicate, 
asbestine,  asbestine  pulp,  etc.     Large  amounts  are  obtained 
from  natural  deposits  in  and  around  Gouverneur,  N.  Y.     It 
has  a  very  low  specific  gravity,  and  is  much  used  in  lead 
and  zinc  paints  to  prevent  those  pigments  from  settling 
hard  in  the  bottom  of  the  package.     Chemically  it  is  very 
inert,  being  unacted  upon  by  any  of  the  ordinary  acids.     It 
is,  however,  decomposable  with  hydrofluoric  acid  in  a  plati- 
num dish  and  by  fusion  with  sodium  carbonate.      Fusion 
with  potassium  bisulphate  decomposes  it  only  partially. 
Continued  heating  at  a  bright  red  heat  will  cause  a  loss  of 
three  to  five  per  cent  in  weight,  due  to  loss  of  water  of 
hydration.     It  is  easily  recognized  under  the  microscope 
by  the  fibrous  or  rod-like  structure  of  the  particles. 

495.  Silica    (Silex).     There   are   two   distinct   kinds   of 
silica  to  be  found  on  the  market,  that  obtained  from  crushed 
quartz,  which  is  a  very  pure  form  of  silica,  and  an  impure 
form  found  in  natural  deposits  especially  in  Illinois.     The 
former  possesses  a  very  pronounced  " tooth;"  under  the 
microscope  the  particles  are  very  sharp  and  jagged,  and  it 
is  quite  transparent  in  oil.     The  second  form  is  composed 
of  rounded  particles  of  a  complex  chemical  nature;  besides 
free  silica  there  are  usually  found  associated  with  it  cal- 
cium carbonate,  aluminum  silicate  and  magnesium  silicate, 
besides  a  small  amount  of  magnesium  carbonate.     This 
product  requires  more  oil  in  grinding,  and  has  much  more 
body,  but  considerably  less  tooth. 

496.  In  the  majority  of  cases  a  complete  qualitative 
analysis  of  the  pigments  present  is  hardly  worth  the  time  it 
requires,  as  there  is  but  little  time  lost  in  following  the  regu- 
lar quantitative  scheme.     If,  however,  a  qualitative  analy- 


QUALITATIVE  ANALYSIS  OF  LEADS  AND  PASTES.     301 

sis  is  desired,  the  following  outline  will  be  found  sufficient 
in  most  instances,  the  removal  of  the  vehicle  previous  to 
these  tests  being  understood. 

497.  Carbonates.  Effervescence  with  concentrated  hydro- 
chloric  acid  indicates    carbonates,  or  hydrogen    sulphide 
if  zinc  sulphide  be  present,  the  latter  being  distinguished 
by  its  odor  and  by  the  fumes  blackening  a  piece  of  filter 
paper  moistened  with  lead  acetate. 

498.  Barytes,  Silica,  Clay,  or  other  Silicates.     Boil  above 
mixtures  five  minutes,  dilute  with  boiling  water,  filter.     An 
insoluble  residue  may  be  barytes,  silica,  clay,  or  other  sili- 
cates.    Test  for  barytes  with  flame  test,  using  a  platinum 
wire.     A  characteristic  green  color  indicates  barium. 

499.  Sulphates.    Test  a  small  portion  of  the  acid  filtrate 
for  combined  sulphuric  acid  with  a  few  drops  of  barium 
chloride. 

500.  Lead.    Test  another  small  portion  of  the  acid  fil- 
trate with  sulphuric  acid.     A  white  precipitate  at  once  or 
on  standing  indicates  lead. 

501.  Zinc.     Take  another  small  portion  of  the  acid  fil- 
trate and  add  a  few  drops  of  potassium  ferrocyanide.     A 
white  precipitate  with  a  bluish  tinge  indicates  zinc. 

502.  Calcium.    The  remaining  portion  of  the  acid  filtrate 
is  made  alkaline  with  ammonia  and    hydrogen    sulphide 
passed  in  for  five  minutes.     Filter  and  test  filtrate  for 
calcium  with  ammonium  oxalate,  setting  aside  in  a  warm 
place. 

503.  Magnesium.    After    completely    precipitating    the 
calcium,  add  a  few  drops  of  hydrogen  sodium  phosphate. 
A  precipitate  on  standing  indicates  the  presence  of  mag- 
nesium compounds. 

The  identification  of  the  forms  in  which  the  lead  may 
occur  can  only  be  determined  by  the  quantitative  scheme 
if  both  sulphates  and  carbonates  are  present. 


CHAPTER  XXX. 

QUANTITATIVE  ANALYSIS  OF  COMBINATION  WHITE  LEADS 
AND  PAINTS. 

504.  Total  Lead.     Weigh  1  gram  of  the  dry  pigment  into 
a  250-c.c.  beaker.     Add  30  c.c.  of  strong  hydrochloric  acid, 
boil  5  minutes,  add  50  c.c.  of  hot  water,  heat  15  minutes 
longer,  settle,  filter  while  hot,  and  wash  thoroughly  with 
boiling  water.     The  washing  should  be  begun  the  instant 
the  solution  has  filtered  through,  in  order  to  avoid  any 
crystallization  of  lead  chloride  in  the  pores  of  the  filter 
paper.     Once  formed  the  crystals  can  only  be  dissolved 
with  difficulty  and  with  the  use  of  an  excess  of  wash  water, 
which,  as  stated,  must  be  at  boiling  temperature.     This 
operation  is  best  conducted  by  the  aid  of  suction.     Casein 
and  other  products  of  a  similar  nature  are  occasionally 
used  in  the  manufacture  of  mixed  paints  in  considerable 
quantities,  and  the  analyst  should  always  be  on  the  lookout 
for  the  possible  presence  of  these  substances. 

505.  The  solution  is  made  just  alkaline  with  ammonia, 
then  just  acid  to  litmus  with  hydrochloric   acid.     It  is 
very  necessary  that  the  solution  be  only  barely  acid,  as  a 
comparatively  small  quantity  of  free  acid  will  keep  consid- 
erable lead  from  precipitating.     Having  been  made  barely 
alkaline,  which  is  indicated  by  the  precipitation  of  the 
lead,  the  solution  is  brought  to  a  faintly  acid  condition 
by  using  dilute  hydrochloric   acid  (1  to   10).     Dilute  to 
about   350    c.c.      Cool,  pass   in    hydrogen   sulphide   gas, 
noting  the  color  of  the  precipitate;  if  gray,  some  zinc  is 
being  thrown  down;  if  reddish  black,  the  solution  is  too 
acid;  add  a  few  drops  of  dilute  acid   or  ammonia  as  the 
case  requires.     Settle,  filter,  and  wash  with  cold    water. 

302 


QUANTITATIVE  ANALYSIS  OF  LEADS  AND  PAINTS.      303 

506.  Place  filter  and  precipitate  in  25  c.c.  of  nitric  acid 
and  25  c.c.  of  water,  heat  gently  until  the  lead  has  all 
dissolved    as   shown   by   the   residual   sulphur   having   a 
yellow   to   whitish   color.     Do   not   boil   hard   enough   to 
thoroughly  disintegrate  the   filter  paper.      If  difficulty  is 
experienced  in  dissolving  the  lead  contained  in  the  sulphur 
particles,  it  is  better  to  collect  them  into  a  ball  with  the 
aid  of  a  stirring  rod  and  remove  to  a  small  beaker  and 
treat  with  a  few  cubic  centimeters  of  concentrated  nitric 
acid,  and  heat  until  dissolved,  then   pour  back  into  the 
larger  beaker. 

507.  Pour  solution  and  filter  paper  on  to  a  suction  funnel 
provided  with  a  platinum  cone.     If  any  fine  part  ides  pass 
through,   pour  the   filtrate   back   again.     This   procedure 
permits  the  washing  of  the  filter  mass  with  a  very  small 
amount  of  water,  thus  saving  considerable  time  in  the 
subsequent  evaporation.     Add  5  c.c.   of  dilute  sulphuric 
acid  to  filtrate,  and  evaporate  until  sulphur  trioxide  fumes 
appear.     Cool,  add   25  c.c.   of  water,   25  c.c.   of  alcohol; 
allow   to   stand   one-half    hour  with   occasional    stirring; 
filter,  using  Gooch  crucible,  wash  with  dilute  alcohol,  dry, 
heat    gently    over    ordinary    lamp,    and    weigh    as    lead 
sulphate. 

508.  Calcium.     The  filtrate  containing  the  zinc,  calcium, 
and   possibly  magnesium  is  made   slightly  alkaline   with 
ammonia,   a  few  drops  of   a  mercuric    chloride  solution 
(1  to  10)  added,  and  a  stream  of  hydrogen  sulphide  gas 
passed  into  the  solution  for  about  ten  minutes. 

The  addition  of  the  mercuric  chloride  renders  the 
precipitate  granular  and  very  easy  to  filter,  and  entirely 
obviates  the  difficulty  of  filtering  a  slimy  zinc  sulphide 
precipitate.  In  the  analysis  of  tints  where  the  zinc  can- 
not be  titrated  until  it  has  been  freed  from  iron,  the  addi- 
tion of  the  mercuric  chloride  will  not  cause  any  trouble, 


304  THE  LEAD  AND   ZINC  PIGMENTS. 

as  treatment  with  hydrochloric  acid  results  in  the  solution 
of  the  zinc  only,  the  mercuric  sulphide  being  insoluble 
in  hydrochloric  acid.  Settle,  decant,  filter,  and  wash. 

509.  Evaporate  the  filtrate   from  abave   precipitate  to 
about  150  c.c.,  make  alkaline  with  ammonia,  add  ammo- 
nium oxalate  (50  c.c.  for  1  gram  of  lime),  usually  20  c.c. 
is  sufficient,  and  set  in  a  warm  place  for  two  or  three  hcurs. 
Filter,  wash,  ignite,  and  weigh  as  calcium  oxide,  or  titrate 
precipitate  with  permanganate  by  placing  filter  and   pre- 
cipitate in  a  400-c.c.  beaker,  adding  200  c.c.   of   boiling 
water  and  25  c.c.  of  dilute  sulphuric  acid,  and  titrate  with 
standard  tenth-normal  potassium  permanganate. 

1  c.c.  tenth-normal  permanganate  =  0.0028  gram  CaO. 
1  c.c.  tenth-normal  permanganate  =  0 . 0050  gram  CaC03. 

Barium  carbonate  is  still  to  be  found  in  certain  mixed 
paints,  and  it  is  advisable  to  test  for  the  presence  of  solu- 
ble barium  before  precipitating  the  calcium. 

510.  Magnesium.   The  filtrate  from  the  calcium  oxalate 
should  be  tested  for  magnesium,  by  treating  with  hydro- 
gen sodium  phosphate.     Allow  to   stand   one-half  hour, 
add  25  c.c.  of  ammonia,  allow  to  stand  one  hour,  then 
filter  on  to  a  Gooch  crucible,  wash  with  dilute  ammonia, 
ignite,  and  weigh. 

Weight  precipitate  X  0.7575  =  weight  magnesium  car- 
bonate. 

511.  Zinc    Oxide.     Reagents.     Standard    Zinc    Solution. 
Dissolve  10  grams  of  chemically  pure  zinc  in  hydrochloric 
acid  in  a  graduated  liter  flask,  add  50  grams  of  ammonium 
chloride  and  make  Up  to  one  liter. 

1  c.c.  =0.01  gram  zinc  or  0.01245  gram  zinc  oxide. 

512.  Standard    Potassium   Ferrocyanide    Solution.     Dis- 
solve 46  to  48  grams  of  crystallized  potassium  ferrocyanide 
in  water,  make  to  1000  c.c. 


QUANTITATIVE  /  NALYSIS  OF  LEADS  AND  PAINTS.     305 

513.  Uranium   Nitrate   Solution.     Dissolve  15  grams  of 
uranium  nitrate  in  100  c.c.  of  water. 

514.  Standardizing  the  Ferrocyanide  Solution.   To  deter- 
mine the  value  of  the  potassium   ferrocyanide  solution, 
pipette  25  c.c.  of  the  zinc  solution  into  a  400  c.c.  beaker. 
Dilute  somewhat  and  make  faintly  alkaline  with  ammonia, 
bring  to  a  faintly  acid  condition  with  hydrochloric  acid, 
and  then  add  3  c.c.  excess  of  the  concentrated  acid,  dilute 
to  a  total  volume  of  about  250  c.c.,  heat  to  80°  C.  and  titrate 
as  follows:  Pour  off  about  10  c.c.  of  the  zinc  solution  into 
a  small  beaker  and  set  aside,  run  the  ferrocyanide  into  the 
remainder  from  a  burette,  a  few  cubic    centimeters  at  a 
time,  until  the  solution  takes  on  a  slight  ash  gray  color, 
or  until  a  drop  of  the  solution  placed  in  contact  with  a 
drop  of  the  uranium  nitrate  solution  on  a  porcelain  plate 
turns  to  a  distinct  brownish  color.     Often  the  end  point 
has  been  passed  by  quite  a  little. 

515.  The  10  c.c.  of  zinc  solution  that  has  been  reserved 
is  now  added  and  the  titration  continued,  drop  by  drop, 
testing  a  drop  6f  the  solution  carefully  on  the  porcelain 
plate  after  each  addition  of  ferrocyanide  solution.     Some 
little  time  is  required  for  the  test  drop  to  change  color, 
so  that  the  end  point  may  have  been  passed  slightly.    This 
may  be  corrected  for  by  making  a  memorandum  of  the 
burette  readings,  having  the  test  drops  arranged  in  regu- 
lar order  and  taking  as  the  proper  reading  the  one  first 
showing   a  distinct   brownish   tinge.     Having  noted   the 
number  of  cubic  centimeters  of  ferrocyanide  required  for 
the  titration  of  the  standard  zinc  solution,  the  value  of 
1  c.c.  may  be  readily  calculated. 

516.  Titration  of  Sample.   One-half  gram  of  the  sample, 
if  high  in  zinc,  or  1  gram,  if  the  zinc  content  is  fairly  low,  is 
dissolved  in  a  covered  beaker  in  10  c.c.  of  hydrochloric 
acid  and  10  c.c.  of  water,  the  solution  diluted  and  treated 


306  THE  LEAD  AND  ZINC  PIGMENTS. 

exactly  as  described  above  for  the  standard  zinc  solution, 
care  being  taken  to  titrate  to  exactly  the  same  depth  of 
color  on  the  porcelain  test  plate.  If  the  method  is  care- 
fully carried  out,  the  procedure  being  uniformly  the  same 
in  each  determination,  the  results  will  be  found  satisfac- 
torily accurate. 

517.  Lead  Sulphate.     Dissolve  0.5  gram  in  water,  25  c.c. 
hydrochloric  acid  in  light  excess.     Dilute  to  200  c.c.  and 
add  a  piece  of  aluminum  foil  which  about  covers  the  bottom 
of  the  beaker.     It  is  important  that  this  be  held  at  the 
bottom    by  a  glass   rod.     Boil    gently  until  the  lead  is 
precipitated.     Completion  of  this  is  shown   by  the  lead 
ceasing  to  coat  or  cling  to  the  aluminum.     Decant  through 
a  filter,   pressing  the  lead  sponge  into  a  cake  to  free  it 
from  solution.     Add  to  filtrate  a  little  sulphur-free  bromine 
water,  ignite,  and  weigh  as  barium  sulphate.     Calculate 
to  lead  sulphate  by  multiplying  by  1.3  as  a  factor,  unless 
calcium  sulphate  is  present,  in  which  case  it  is  advisable  to 
make  use  of  Thompson's  separation. 

518.  In  the  absence  of  barium  sulphate,  the  combined 
sulphuric    acid    may    be    estimated    by    H.    Mannhardt's 
method :  Grind  1  gram  of  pigment  with  1  gram  of  sodium 
carbonate,  very  intimately  in  an  agate  mortar.     Boil  gently 
for  ten  minutes,  the  combined  sulphuric  acid,  and  in  the  case 
of  colors  containing  chromates,  the  chromic  acid  will  pass 
into  solution  and  may  be  estimated  in  the  filtrate  in  the 
usual  manner.     If  necessary  collect  the  insoluble  portion  on 
a  filter,  dry,  detach  and  triturate  a  second  time. 

519.  Basic   Carbonate   of   Lead     (White     lead).     After 
deducting  the  amount  of  lead  present  in  the  pigment  as 
sulphate  of  lead,  calculate  the  rest  of  the  lead  as  white  lead 
by  multiplying  the  remaining  sulphate  by  0.852,  unless 
sublimed  lead  is  suspected  to  be  present,  in  which  case  the 
combined  lead  oxide  must  be  taken  into  consideration. 


QUANTITATIVE  ANALYSIS  OF  LEADS  AND  PAINTS     307 

520.  Insoluble  Residue.  The  insoluble  residue  from  the 
original  hydrochloric  acid  treatment  may  contain  barytes, 
magnesium  silicate,  silica  and  clay.     Ignite,  filter  paper  and 
residue  until  white,  weigh  as  total  insoluble  matter;  grind 
in  agate  mortar  with  about  10  times  its  weight  of  sodium 
carbonate,  fuse  for  1  hour  in  a  platinum  crucible,   and 
dissolve  out  in  hot  water. 

521.  Barium  Sulphate.   The  solution  from  the  fusion  is 
filtered.     The  residue  coasists  of  barium  carbonate,  mag- 
nesium carbonate,  etc.,  and  is  washed  with   hot  water. 
The  filtrate  and  washings  are  saved.     Pierce  filter  paper 
and  wash  precipitate  into   clean  beaker  with  hot    dilute 
hydrochloric  acid;  finish  washing  with  hot  water,  4ieat  to 
boiling,  add  10  c.c.  of  dilute  sulphuric  acid  to  precipitate 
barium,  filter,  ignite,  and  weigh  as  barium  sulphate. 

522.  Silica.   The  filtrate  from  the  barium   sulphate  is 
added  with  care  to  the  filtrate  reserved  in  the  preceding 
paragraph,  making  distinctly  acid;  evaporate  to  complete 
dryness,  cool,  add  15  c.c.  of  hydrochloric  acid,   heat  to 
boiling,  cool,  settle,  filter,  ignite,  and  weigh  as  silica. 

523.  Alumina.  The  filtrate  from  the  silica  will  contain 
all  of  the  alumina  except  that  which  was  dissolved  in  the 
original  treatment  with  hydrochloric  acid.     This  is  quite 
constant,  varying  from  .004  to  .005  gram  per  gram  of  clay. 
The  acid  filtrates  are  made  slightly  alkaline  with  ammonia, 
and  boil  until  odor  disappears.     Settle,  filter,  wash,  ignite, 
and  weigh  as  alumina. 

Weight  alumina  X  2.5372  =  weight  clay. 
Weight  clay  X  .4667  =  weight  of  silica  in  clay. 

Any  difference  greater  than  5  per  cent  may  be  considered 
as  free  or  added  silica,  according  to  Scott. 

524.  Calcium    and    Magnesium    Oxides.     If    qualitative 
test  shows  presence  of '  magnesium  in  insoluble  residue 


308  THE  LEAD   AND  ZINC  PIGMENTS. 

from  the  first  hydrochloric  acid  treatment  it  was  present 
probably  as  magnesium  silicate.  Treat  filtrate  from  the 
aluminum  hydroxide  for  calcium  and  magnesium  oxides. 
Magnesium  silicate  contains  3-5  per  cent  combined  water. 

525.  Hydrofluoric  Acid  Treatment.  Instead  of  resorting  to 
fusion  with  sodium  carbonate,  the  insoluble  residue,  which 
should  be  weighed  up  in  a  clean  platinum  crucible,  may  be 
treated  with  several  drops  of  pure  concentrated  hydrofluoric 
acid  and  of  sulphuric  acid  and  heated  gently  on  a  sand 
bath  under  the  hood,  using  only  sufficient  heat  to  slowly 
volatilize  the  silica  and  sulphuric  acid.  Dissolve  out  in 
water  acidulated  with  hydrochloric  acid.  The  residue, 
which  is  barium  sulphate,  is  filtered  off  and  estimated  as 
such.  The  filtrate  will  contain  any  aluminum,  calcium 
and  magnesium  present  and  which  may  be  estimated  and 
calculated  as  oxides  as  above  described.  The  combined 
weight  of  the  barium  sulphate,  alumina,  calcium  and  mag- 
nesium oxides  subtracted  from  the  weight  of  the  insolu- 
ble residue  used  gives  the  weight  of  silica.  This  operation 
is  much  shorter  than  resorting  to  a  fusion. 

526.  Mixed  Carbonates  and  Sulphates.  Occasionally 
paints  are  met  with  which  contain  calcium  sulphate, 
calcium  carbonate,  sulphate  of  lead  and  white  lead  (basic 
carbonate  of  lead),  in  which  case  it  is  necessary  to  make 
a  separation  of  the  calcium  compounds,  which  may  be 
effected  by  Thompson's  method  as  follows : 

527.  To  1  gram  of  the  sample  are  added  20  c.c.  of  a 
mixture  of  nine  parts  alcohol  (95  per  cent)  and  one  part 
of  concentrated  nitric  acid.  Stir,  and  allow  to  stand  20 
minutes.  Decant  on  a  filter  and  repeat  the  treatment 
with  the  acid-alcohol  mixture  four  times,  allowing  it  to 
stand  each  time  before  decanting.  The  calcium  carbonate 
will  go  into  solution,  while  the  calcium  sulphate  or  gypsum 
remains  undissolved.  Add  filter  and  contents  to  the 


QUANTITATIVE  ANALYSIS   OF  LEADS  AND  PAINTS.     309 

residue  remaining  in  the  beaker  ;  dissolve  in  hydrochloric 
acid  with  sufficient  water  to  insure  the  solution  of  the 
calcium.  Make  alkaline  with  ammonia,  pass  in  hydrogen 
sulphide  for  10  minutes,  boil,  settle,  filter.  The  filtrate 
and  washings  are  concentrated  to  about  150  c.c.  and  the 
calcium  precipitated  with  ammonium  oxalate  in  the  usual 
manner.  The  ignited  precipitate  is  calculated  to  hydrated 
calcium  sulphate. 

528.  Calculations.  The  ignited  precipitate  of  calcium 
oxide  obtained  from  the  portion  insoluble  in  the  acid- 
alcohol  mixture  is  subtracted  from  the  total  calcium 
weighed  as  oxide;  the  remaining  calcium  oxide  is  calcu- 
lated to  calcium  carbonate.  The  total  carbon  dioxide  is 
determined  in  a  portion  of  the  sample,  the  portion  due  to 
the  calcium  carbonate  is  deducted  from  the  total  amount, 
and  the  remainder  calculated  to  basic  carbonate  of  lead. 
The  combined  sulphuric  acid  due  to  the  sulphate  of  lime 
is  deducted  from  the  total  combined  sulphuric  acid,  and 
the  remainder  calculated  to  sulphate  of  lead. 

Wt.  calcium  oxide  X  3.0715  =  hydrated  calcium  sulphate. 

Wt.  calcium  oxide  X  1.784  =  calcium  carbonate. 

Wt.  calcium  carbonate  X  0.440  =  carbon  dioxide. 

Wt.  carbon  dioxide  X  8.8068  =  basic  carbonate  of  lead. 

Wt.   of  hydrated  sulphate  of   lime  X  0.4561  =  combined 

sulphuric  acid. 
Wt.   of   combined    sulphuric    acid  X  3.788  =  sulphate    of 

lead. 


CHAPTER  XXXI. 

LABORATORY  EQUIPMENT  AND   MANIPULATION. 

529.  The  two  essential  requisites  required  of  a  paint 
chemist  are  accuracy  and  rapidity.     Often  a  pigment  or 
combination  of  pigments  in  oil  or  other  thinners  is  brought 
into  the  laboratory  and  a  complete  analysis  desired  on 
the  same  day.     Unless  the  laboratory  is  equipped  with 
all  possible  labor  and  time-saving  devices  this  will  prove 
generally  impossible.     To  the  experienced  paint  chemist 
many  of  these  devices  naturally  suggest  themselves,  but  to 
the  young  chemist  who  is  just  beginning  his  paint  work 
the  following  points,  which  have  been  of  assistance  to  the 
author  in  his  laboratory  work,  may  be  of  interest. 

530.  Weight  per  Gallon.     The  use  of  the  "  cubic  inch  " 
with  counterpoise  weight  will  serve  for  this  determina- 
tion excellently. 

531.  Specific    Gravities.    Special    hydrometers    reading 
0.850  to  0.900  and  0.900  to  0.950  can  be  secured  which 
will  afford  the  desired  accuracy  with  ordinary  paint  vehi- 
cles.     For   other   determinations    the   Westphal    balance 
should  bs  used. 

532.  Rapid  Extraction  of  Pigment.   The  pigment  can  be 
rapidly  freed  from  the  vehicle  by  the  use  of  a  steam- 
heated  high-speed  centrifuge.    The  cylinders  should  be  of 
aluminum   provided   with   screw  bottoms,    rendering   the 
removal  of  the  pigment  easy.     The  use  of  several  of  these 
cylinders,  tightly  corked,  will  afford  sufficient  vehicle  for 
estimation  of  the  amount  and  nature  of  volatile  oils  present. 
The  centrifuge  should  be  strongly  constructed,  as  the  pres- 
sure on  the  containing  cups  due  to  centrifugal  force  may 

310 


LABORATORY   EQUIPMENT  AND  MANIPULATION.     311 

reach  100  pounds  to  the  square  inch.  If  only  the  pigment 
is  desired,  thinning  the  sample  with  benzine  before  centri- 
fuging  will  materially  hasten  the  operation.  On  removal 
from  the  tubes  the  pigment  should  be  washed  slightly 
with  benzine  or  acetone  on  a  suction  filter. 

533.  Estimation  of   Water  in  Paints.     This  estimation 
may  be  accurately  performed  in  a  very  few  minutes  by 
use  of  the  amyl  reagent  as  described  in  Chapter  XXVIII. 

534.  Estimation  of    Volatile    Oils.     This  determination 
can   be   made   very   rapidly   by  distilling  with   steam   at 
130°  C.  as  described  in  "  Analysis  of  Mixed  Paints,  Color 
Pigments  and  Varnishes,"  Holley  and  Ladd,  page  39.     The 
apparatus  for  this  determination  should  have  an*allotted 
place  in  the  laboratory  and  be  kept  set  up  ready  for  use. 

535.  Rapid  Drying.   A  double  wall  copper  drying  oven, 
to  which  is  attached  a  Soxhlet  ball  condenser,  a  soldered 
connection  being  preferable,  possesses  obvious  advantages 
over  the  more  ordinary  type  of  water  oven,  especially  if  a 
suitable  mixture  of  toluene  and  xylene,  boiling  at  115°C., 
be  used  instead  of  water.     This  wrill  assure  a  very  rapid 
drying  of  any  material  in  the  oven  and  the  top  of  the  oven 
will  serve  as  an  excellent  substitute  for  a  hot  plate  for 
evaporations.     The  oven  should  be  set  in  a  small  lead  pan 
so  as  to  avoid  danger  of  fire  in  case  of  a  leakage. 

536.  Filtering  by  Suction.   Much  time  is  saved  by  using 
the  filter  pump  whenever  possible.     It  also  reduces  the 
amount  of  wash  water  required  so  that  the  resulting  fil- 
trates will  not  be  too  bulky  for  convenient  handling  or 
require    concentration    before    undergoing    further    treat- 
ment.    Instead   of  the  ordinary  filter-bottle  or  flask,   a 
500  to  1000-c.c.  separatory  funnel  of  the  conical  type  can 
be  used  to  advantage,  it  being  supported  by  a  clamp  at- 
tached to  the  neck.     The  advantage  consists  in  the  fact 
that  the  filtrate  can  easily  be  drawn  off  from  the  bottom 


312  THE  LEAD   AND   ZINC  PIGMENTS. 

without  disturbing  the  funnel  containing  the  precipitate, 
which  is  advantageous  in  the  treatment  of  precipitates 
which  tend  to  pass  through  the  filter-paper,  especially 
when  subjected  to  washing,  as  for  example  chromium 
hydroxide,  or  when  it  is  desired  to  examine  a  portion  of 
the  filtrate  before  completing  the  filtration. 

537.  Use  of  Gooch  Crucible.   The  Gooch  crucible  affords 
the  most  rapid  method  for  obtaining  precipitates  in  the 
most  desirable  form  for  drying  or  ignition.     Many  precipi- 
tates which  pass  through  an  ordinary  Gooch  crucible,  as 
for  example  barium  sulphate,  can  be  easily  retained  by 
inserting  a  disk  of  ashless  filter  paper  on  the  layer  of 
asbestos  after  the  weighing  of  the  crucible  if  it  is  to  be 
subsequently  ignited.     This  disk   should   be   cut   slightly 
larger  than  the  crucible  so  that  when  moistened  and  fitted 
down  tightly,  it  will  be  rimmed  up  slightly  all  around  the 
edge.     In    collecting    gelatinous    precipitates    the    Gooch 
should  not  be  allowed  to  suck  dry  until  the  filtering  opera- 
tion is  completed. 

538.  The  preparation  of  the  asbestos  for  use  in  the  Gooch 
crucible  is  a  most  important  item.     The  short-fiber  asbes- 
tos sold  for  this  purpose  by  the  chemical  supply  houses 
should  be  shaken  up  in  a  large  bottle  of  water,  the  heavy 
fibers  allowed  to  settle  for  two  or  three  seconds,  the  con- 
tents tjien  poured  into  another  bottle,  leaving  the  heavy 
fibers  behind,  then  allowed  to  settle  until  all  but  the  finest 
particles  have  been  deposited,  which  are  then  poured  off, 
leaving  a  medium-fiber  asbestos  which  when  treated  by 
boiling  with  hydrochloric  acid  to  remove  iron  and  any 
other  impurities  soluble  in  acid  is  excellently  adapted  for 
rapid  filtering. 

539.  Bottles  for  Standard  Solutions.   Many  of  the  stand- 
ard solutions  used  in  paint  analysis,  such  as  potassium 
ferrocyanide,    permanganate,    sodium    thiosulphate,    etc., 


LABORATORY  EQUIPMENT  AND  MANIPULATION.     313 

have  to  be  frequently  restandardized  on  account  of  the 
effect  of  light  upon  them  unless  kept  in  a  dark  closet, 
which  is  not  always  easy  to  manage.  By  giving  the  bot- 
tles two  coats  of  an  opaque,  quick-drying  black  paint,  the 
solutions  will  keep  their  strength  for  considerable  inter- 
vals of  time,  even  in  a  strong  light. 


APPENDIX. 


316 


THE  LEAD   AND   ZINC  PIGMENTS. 


540.  Table  I.  Atomic  Weights.1 


Name. 


Symbol.  O  =  16. 


H=  1. 


Aluminium Al 

Antimony Sb 

Argon A 

Arsenic As 

Barium Ba 

Bismuth Bi 

Boron B 

Bromine Br 

Cadmium Cd 

Caesium Cs 

Calcium Ca 

Carbon C 

Cerium Ce 

Chlorine Cl 

Chromium Cr 

Cobalt Co 

Columbium Cb 

Copper Cu 

Erbium E 

Fluorine F 

Gadolinium Gd 

Gallium Ga 

Germanium Ge 

Glucinum Gl 

Gold Au 

Helium He 

Hydrogen H 

Indium In 

Iodine I 

Iridium Ir 

Iron Fe 

Krypton Kr 

Lanthanum La 

Lead Pb 

Lithium Li 

Magnesium Mg 

Manganese Mn 

Mercury Hg 

Molybdenum Mo 


27.1 
120.2 

39.9 

75.0 
137.4 
208.5 

11.0 

79.96 
112.4 
132.9 

40.1 

12.0 
140.25 

35.45 

52.1 

59.0  ' 

94.0 

63.6 
166 

19.0 
156.0 

70.0 

72.5 
9.1 
197.2 
4.0 
1.008 
114.0 
126.85 
193.0 

55.9 

81.8 
138.9 
206.9 
7.03 

24.36 

55.0 
200.0 

96.0 


26.9 

119.3 

39.6 

74.4 

136.4 

206.9 

10.9 

79.36 

111.6 

131.9 

39.8 

11.91 

139.2 

35.18 

51.7 

58.56 

93.3 

63.1 

164.8 

18.9 

155.0 

69.5 

71.9 

9.03 
195.7 
4.0 
1.0 
113.1 
125.9 
191.5 
55.5 
81.2 
137.9 
205.35 
6.98 
24.18 
54.6 
198.5 
95.3 


J.  Am.  Chem.  Soc.,  xxvi,  3. 


APPENDIX. 


317 


Table    I    (Continued) . 


Name. 

Symbol. 

O  =  16. 

H=  1. 

Neodymium  

Nd 

143  6 

142  5 

Neon  

Ne 

20  0 

19  9 

Nickel  

Ni 

58  7 

58  3 

Nitrogen  
Osmium      

N 
Os 

14.04 
191  0 

13.93 
189  6 

Oxvffen 

O 

16  0 

15  88 

Palladium 

Pd 

106  5 

105  7 

Phosphorus 

P 

31  0 

30  77 

Platinum 

Pt 

194  8 

193  3 

Potassium 

K 

39  15 

38  86 

Praseodymium 

Pr 

140  5 

139  4 

Radium 

Ra 

225  0 

223  3 

Rhodium 

Rh 

103  0 

102  2 

Rubidium 

Rb 

85  4 

84  8 

Ruthenium  
Samarium 

Ru 
Sm 

101.7 
150  0 

100.9 
148  9 

Scandium 

Sc 

44  1 

43  8 

Selenium 

Se 

79  2 

78  6 

Silicon 

Si 

28  4 

28  2 

Silver 

Ac 

107  93 

107  12 

Sodium 

Na 

23  05 

22  88 

Strontium 

Sr 

87  6 

86  94 

Sulphur 

s 

32  06 

31  83 

Tantalum  
Tellurium                   .    .    . 

Ta 
Te 

183.0 
127  6 

181.6 
126  6 

Terbium          

Tb 

160 

158  8 

Thallium      

Tl 

204  1 

202  6 

Thorium  

Th 

232  5 

230  8 

Thulium    

Tm 

171 

169  7 

Tin  

Sn 

119  0 

118  1 

Titanium  
Tungsten  

Ti 
W 

48.1 
184 

47.7 
182  6 

Uranium  

u 

238  5 

236  7 

Vanadium  

V 

51  2 

50  8 

Xenon  

X 

128.0 

127  0 

Ytterbium 

Yb 

173  0 

171  7 

Yttrium 

Yt 

89  0 

88  3 

Zinc 

Zn 

65  4 

64  9 

Zirconium 

Zr 

90  6 

89  9 

318 


THE  LEAD  AND  ZINC  PIGMENTS. 


541.   Table  II.   Formulas  and  Molecular  Weights. 


Name. 

Formula. 

Mol.  Wt. 

Acid,  acetic  

HC2H3O2 

60 

Acid,  arsenious  

H3ASO3 

125  9 

Acid,  boric  

H3BO3 

62 

Acid   citric 

H,CfiH,O7  +  H9O 

210 

Acid   hydrochloric 

HC1 

36  4 

Acid,  hydrosulphuric  
Acid   nitric 

H2S 
HNO3 

34 
63 

Acid    nitrous 

HNO2 

47 

Acid   oleic    

HC,8H33O2 

282 

Acid,  oxalic  
Acid   sulphuric     

H2C2O4  +  2H2O 
H2SO4 

126 

98 

Acid   sulphurous  

H2SO, 

82 

Acid    tannic          

C14H1(iO0 

322 

Acid,  tartaric  
Amyl  acetate  
Antimony  chloride  
Antimony  oxide  

HAHA 

C,HnC2H3O2 
SbCl, 
SbjO. 

150 
130 
226.2 

288 

Antimony  sulphide  

Sb2S, 

336 

Arsenious  oxide 

AsoO, 

309  8 

Arsenious  sulphide 

As2S3 

245  8 

Barium  carbonate 

BaCO3 

196  8 

Barium  chloride 

BaCl2  +  2H2O 

243  6 

Barium  nitrate  
Barium  sulphate     

Ba(N03)2 
BaSO. 

260.8 
232  8 

Benzole                 

C6H6 

78 

Calcium  carbonate  
Calcium  hydroxide  
Calcium  sulphate  
Calcium  sulphate,  crystallized. 
Carbon  dioxide  
Carbon  disulphide 

CaCO3 
Ca(OH)2 
CaSO4 
CaSO4  +  2H2O 
CO2 
CS2 

100 
74 
136 
172 
44 
76 

APPENDIX. 


319 


Table    II    (Continued). 


Name. 

Formula. 

Mol.  Wt. 

Chromium  trioxide 

CrO 

100  4 

Copper  sulphate 

CuSO  4-  5H,O 

249  2 

Cuprous  oxide 

Cu2O 

142  4 

Glycerin        

C,H,(OH) 

92 

Lead  acetate. 

Pb(C2H  O2)2  4-  3H2O 

378  5 

Lead  acetate,  basic  
Lead  carbonate,  basic  
Lead  carbonate,  normal  
Lead  chromate  
Lead  dioxide  ... 

Pb.O(C2HA)2 
2PbCO3.Pb(OH)2 
PbCO, 
PbCrO4 
PbO2 

547 
773.5 
*     266.5 
323.0 
238  5 

Lead  nitrate  

Pb(NO,)9 

330  5 

Lead  oxide  
Lead,  red  oxide  of  

PbO 
Pb-A, 

222.5 
683  5 

Lead  sulphate  
Potassium  bichromate  

piM 

K2Cr2O7 

302.5 
294  8 

Potassium  carbonate  

K2CO3  +  3H,O 

330  0 

Potassium  chromate  

K2CrO. 

194  4 

Potassium  ferrocyanide 
Potassium  hydroxide  

K^e«5N).+  3H,0 

421.9 
56 

Potassium  iodide  

KI 

165  6 

Potassium  permanganate  
Silver  nitrate 

KMnO4 
AgNO 

157 
169  7 

Sodium  acetate  . 

NaC2H  O2  +  3H  O 

136 

Sodium  arseniate 

NaoHAsO  ~\-  7H2O 

312 

Sodium  borate 

Na.jB  O  -I-  10H2O 

382 

Sodium  carbonate,  dry  
Sodium  carbonate,  crystallized 
Sodium  nitrate  

Na,jCO3 
NaaCO,  +  10H2O 
NaNO3 

106 
286 
85 

Zinc  oxide    

ZnO 

80  9 

Zinc  sulphate  

ZnSCX  +  7H,O 

286  9 

Zinc  sulphide  

ZnS 

96  9 

320 


THE  LEAD  AND  ZINC  PIGMENTS. 


542.   Table  III.   Factors  for  Gravimetric  Analysis. 


Determined  as 

Required. 

Factor. 

ALO3 

Al 

0  5303 

AsJS, 

As 

0  6093 

AsoO, 

0  8043 

Mg2As2O7 

As2O3 

0  6372 

Ba 

0  5885 

BaSO4.  . 

PbSO4 

1  3004 

BaSO4.    . 

CaSO4 

0  5837 

BaSO4.  .  .               

CaSO42H2O 

0  7382 

BaSO4  

SO, 

0  3433 

BaSO4  

so! 

0  2747 

CaO  

Ca 

0  7143 

CaO  

CaCO3 

1     784 

CaCO3 

CO2 

0     440 

CaO 

CaSO  2H2O 

3  0715 

CaSO42H2O 

SO 

0  4561 

CO9 

2PbCO3Pb(OH)2 

8  8068 

Cr2Os 

PbCrO4 

4  2288 

Cr,O, 

CrO3 

1  3137 

Cr,O, 

PbCrO  PbO 

7  1438 

FeA 

Fe 

0  7000 

K2SO4 

K 

0  4491 

K2PtCL 

K 

0  1612 

K2PtCL 

K9O 

0  1941 

MffoP2O7 

Mg 

0  2188 

Mg2PA. 

MgO 

0  3624 

Mg,PA 

MgCO, 

0  7575 

Na2SO4  

^o         3 

Na 

0  3243 

Na^CX  

Na,O 

0  4368 

PbSO4  

Pb 

0  6832 

PbSO4  

PbO 

0  7359 

PbSO4.  .  . 

Pb,O4 

0.7536 

PbSO4.  . 

2PbCO3Pb(OH)2 

0.8526 

PbSO4 

PbCrO4 

1  0676 

Mg2P2O7 

PoO, 

0  6376 

SO3     . 

PbSO4 

3     788 

Zn  

ZnSO4 

2     478 

Zn  

ZnO 

1  2452 

ZnSO4.  ... 

ZnO 

0     503 

APPENDIX. 


321 


543.   Table    IV.   Specific    Gravities    Corresponding    to 
Degrees  Baume  for  Liquids  Lighter  than  Water. 


Degrees 
Baume. 

Specific  gravity. 

Degrees 
Baume. 

Specific  gravity. 

10 

1.000 

37 

0.843 

11 

0.993 

38 

0.838 

12 

0.986 

39 

0.833 

13 

0.979 

40 

0.829 

14 

0.973 

41 

0.824 

15 

0.967 

42 

0.819 

16 

0.960 

43 

0.815 

17 

0.954 

44 

(T.810 

18 

0.948 

45 

0.806 

19 

0.942 

46 

0.801 

20 

0.935 

47 

0.797 

21 

0.929 

48 

0.792 

22 

0.924 

49 

0.788 

23 

0.918 

50 

0.784 

24 

0.912 

51 

0.781 

25 

0.906 

52 

0.776 

26 

0.901 

53 

0.771 

27 

0.895 

54 

0.769 

28 

0.889 

55 

0.763 

29 

0.884 

56 

0.759 

30 

0.879 

57 

0.755 

31 

0.873 

58 

0.751 

32 

0.868 

59 

0.748 

33 

0.863 

60 

0.744 

34 

0.858 

61 

0.740 

35 

0.853 

62 

0.736 

36 

0.848 

322 


THE  LEAD  AND  ZINC  PIGMENTS. 


544.   Table    V.     Specific   Gravities   Corresponding    to 
Degrees  Baume  for  Liquids  Heavier  than  Water. 


Degrees 
Baume. 

Specific  gravity. 

Degrees 
Baume. 

Specific  gravity. 

0 

1.000 

37 

.337 

1 

1.007 

38 

.349 

2 

.014 

39 

.361 

3 

.020 

40 

.375 

4 

.028 

41 

.388 

5 

.034 

42 

.401 

6 

.041 

43 

.414 

7 

.049 

44 

.428 

8 

.057 

45 

.442 

9 

.064 

46 

1.456 

10 

.072 

47 

1.470 

11 

.080 

48 

1.485 

12 

.088 

49 

1.500 

13 

.096 

50 

1.515 

14 

.104 

51 

1.531 

15 

.113 

52 

.546 

16 

.121 

53 

.562 

17 

.130 

54 

.578 

18 

.138 

55 

.596 

19 

.147 

56 

.615 

20 

.157 

57 

.634 

21 

.166 

58 

.653 

22 

.176 

59 

.671 

23 

.185 

60 

.690 

24 

.195 

61 

.709 

25 

1.205 

62 

.729 

26 

1.215 

63 

.750 

27 

1.225 

64 

.771 

28 

1.235 

65 

.793 

29 

.245 

66 

.815 

30 

.256 

67 

1.839 

31 

.267 

68 

1  .  8«34 

32 

.278 

69 

1.885 

33 

.289 

70 

1.909 

34 

.300 

71 

1.035 

35 

.312 

72 

1.960 

36 

1.324 

APPENDIX. 


323 


545.  Table  VI.  Relation  of  Baume  Degrees  to  Specific 
Gravity,  and  the  Weight  per  United  States  Gallon  at 
15-5°  C. 


Baurne. 

£$ 

11 

02  a 

Pounds  in 
gallon. 

I 

Specific 
gravity. 

a 

ii 
|i 

Baume. 

£  * 

*! 

02  fe 

c 

ii 
P 

10 

1  .  0000 

8.33 

38 

0.8333 

6.94 

66 

0.7142 

5.95 

11 

0.9929 

8.27 

39 

0.8284 

6.90 

67 

0.7106 

5.92 

12 

0.9859 

8.21 

40 

0.8235 

6.86 

68 

0.7070 

5.89 

13 

0.9790 

8.16 

41 

0.8187 

6.82 

69 

0.7035 

5.86 

14 

0.9722 

8.10 

42 

0.8139 

6.78 

70 

0.7000 

5.83 

15 

0.9655 

8.04 

43 

0.8092 

6.74 

71 

0.6965 

5.80 

16 

0.9589 

7.99 

44 

0.8045 

6.70 

72 

0.6930 

5.78 

17 

0.9523 

7.93 

45 

0.8000 

6.66 

73 

0.6896 

5.75 

18 

0.9459 

7.88 

46 

0.7954 

6.63 

74 

0.6863 

5.72 

19 

0.9395 

7.83 

47 

0.7909 

6.59 

75 

0.6829 

5.69 

20 

0.9333 

7.78 

48 

0.7865 

6.55 

76 

0.6796 

5.66 

21 

0.9271 

7.72 

49 

0.7821 

6.52 

77 

0.6763 

5.63 

22 

0.9210 

7.67 

50 

0.7777 

6.48 

78 

0.6730 

5.60 

23 

0.9150 

7.62 

51 

0.7734 

6.44 

79 

0.6698 

5.58 

.24 

0.9090 

7.57 

52 

0.7692 

6.41 

80 

0.6666 

5.55 

25 

0.9032 

7.53 

53 

0.7650 

6.37 

81 

0.6635 

5.52 

26 

0.8974 

7.48 

54 

0.7608 

6.34 

82 

0.6604 

5.50 

27 

0.8917 

7.43 

55 

0.7567 

6.30 

83 

0.6573 

5.48 

28 

0.8860 

7.38 

56 

0.7526 

6.27 

84 

0.6542 

5.45 

29 

0.8805 

7.34 

57 

0.7486 

6.24 

85 

0.6511 

5.42 

30 

0.8750 

7.29 

58 

0.7446 

6.20 

86 

0.6481 

5.40 

31 

0.8695 

7.24 

59 

0.7407 

6.17 

87 

0.6451 

5.38 

32 

0.8641 

7.20 

60 

0.7368 

6.14 

88 

0.6422 

5.36 

33 

0.8588 

7.15 

61 

0.7329 

6.11 

89 

0.6392 

5.33 

34 

0.8536 

7.11 

62 

0.7290 

6.07 

90 

0.6363 

5.30 

35 

0.8484 

7.07 

63 

0.7253 

6.04 

95 

0.6222 

5.18 

36 

0.8433 

7.03 

64 

0.7216 

6.01 

37 

0.8383 

6.98 

65' 

0.7179 

5.98 

324 


THE  LEAD   AND  ZINC  PIGMENTS. 


546.   Table  VII.   Specific  Gravity  of  Acetic  Acid,  Tem- 
perature 15°  C. 


Per 
cent. 

Specific 
gravity. 

Per 
cent. 

Specific 
gravity. 

Per 
cent. 

Specific 
gravity. 

Per 

cent. 

Specific 
gravity. 

100 

1.0553 

75 

1.0746 

50 

1.0615 

25 

1.0350 

99 

.0580 

74 

1.0744 

49 

1.0607 

24 

1.0337 

98 

.0604 

73 

1.0742 

48 

1.0598 

23 

1.0324 

97 

.0625 

72 

1.0740 

47 

1.0589 

22 

1.0311 

96 

.0644 

71 

1.0737 

46 

1.0580 

21 

1.0298 

95 

.0660 

70 

.0733 

45 

1.0571 

20 

1.0284 

94 

.0674 

69 

.0729 

44 

1.0562 

19 

1.0270 

93 

.0686 

68 

.0725 

43 

1.0552 

18 

1.0256 

92 

.0696 

67 

.0721 

42 

.0543 

17 

1.0242 

91 

.0705 

66 

.0717 

41 

.0533 

16 

.0228 

90 

.0713 

65 

.0712 

40 

.0523 

15 

.0214 

89 

.0720 

64 

.0700 

39 

.0513 

14 

.0201 

88 

.0726 

63 

.0702 

38 

.0502 

13 

.0185 

87 

1.0731 

62 

.0697 

37 

.0492 

12 

.0171 

86 

1.0736 

61 

.0691 

36 

1.0481 

11 

.0157 

85 

1.0739 

60 

1.0685 

35 

1.0470 

10 

1.0142 

84 

1.0742 

59 

1.0679 

34 

1.0459 

9 

1.0127 

83 

1.0744 

58 

1.0673 

33 

1.0447 

8 

1.0113 

82 

.0746 

57 

1.0666 

32 

1.0436 

7 

1.0098 

81 

.0747 

56 

1.0660 

31 

1.0424 

6 

1.0083 

80 

.0748 

55 

1.0653 

30 

1.0412 

5 

1.0067 

79 

.0748 

54 

1.0646 

29 

1  .  0400 

4 

1.0052 

78 

.0748 

53 

1.0638 

28 

1.0388 

3 

1.0037 

77 

.0748 

52 

1.0631 

27 

1.0375 

2 

1.0022 

76 

.0747 

51 

1.0623 

26 

1.0363 

1 

1  .  0007 

APPENDIX. 


325 


547.   Table  VIII.     Specific  Gravity  of  Nitric  Acid. 


Speci  fie 
gravity. 

De- 
grees 
B. 

100  pts. 
contain 
grms. 
HN03. 

Speci  fie 
gravity. 

De- 
grees 
B. 

100   pts. 
contain 
grms. 
HNO3. 

1.007 

1 

1.5 

.231 

27 

37.0 

1.014 

2 

2.6 

.242 

28 

38.6 

.022 

3 

4.0 

.252 

29 

40.2 

.029 

4 

5.1 

.261 

30 

41.5 

.036 

5 

6.3 

.275 

31 

"43.5 

.044 

6 

7.6 

.286 

32 

45.0 

.052 

7 

9.0 

.298 

33 

47.1 

.060 

8 

10.2 

.309 

34 

48.6 

.067 

9 

11.4 

.321 

35 

50.7 

.075 

10 

12.7 

.334 

36 

52.9 

.083 

11 

14.0 

.346 

37 

55.0 

.091 

12 

15.3 

.359 

38 

57.3 

1.100 

13 

16.8 

.372 

39 

59.6 

1.108 

14 

18.0 

.384 

40 

61.7 

1.116 

15 

19.4 

.398 

41 

64.5 

1.125 

16 

20.8 

.412 

42 

67.5 

1.134 

17 

22.2 

.426 

43 

70.6 

1.143 

18 

23.6 

.440 

44 

74.4 

1.152 

19 

24.9 

.454 

45 

78.4 

.161 

20 

26.6 

.470 

46 

83.0 

.171 

21 

27.8 

.485 

47 

87.1 

.180 

22 

29.2 

.501 

48 

92.6 

.190 

23 

30.7 

.516 

49 

96.0 

.199 

24 

32.1 

.524 

49.5 

98.0 

.210 

25 

33.8 

.530 

49.9 

100.0 

.221 

26 

35.5 

326 


THE  LEAD  AND  ZINC  PIGMENTS. 


548.    Table  IX.     Specific  Gravity  of  Hydrochloric  Acid. 

Percentage  by  weight  at  15°.5C.  compared  with  water  at  4°C. 
(Lunge  &  Marchlewski.) 


Specific 
gravity. 

Percent- 
tage  HC1. 

Specific 
gravity. 

Percent- 
age HC1. 

Speci  fie 
gravity. 

Percent- 
age HC1. 

1.000 

0.16 

1.070 

14.17 

1.140 

27.66 

1.005 

1.15 

1.075 

15.16 

1.145 

28.61 

1.010 

2.14 

1.080 

16.15 

1.150 

29.57 

1.015 

3.12 

1.085 

17.13 

1.155 

30.55 

1.020 

4.13 

1.090 

18.11 

1.160 

31.52 

1.025 

5.15 

1.095 

19.06 

1.165 

32.49 

1.030 

6.15 

1.100 

20.01 

1.170 

33.46 

1.035 

7.15 

1.105 

20.97 

1.175 

34.42 

.040 

8.16 

.110 

21.92 

1.180 

35.39 

.045 

9.16 

.115 

22.86 

1.185 

36.31 

.050 

10.17 

.120 

23.82 

1.190 

37.23 

.055 

11.18 

.125 

24.78 

1.195 

38.16 

.060 

12.19 

.130 

25.75 

1.200 

39.11 

.065 

13.19 

.135 

26.70 

APPENDIX. 


327 


549.   Table  X.     Sulphuric  Acid. 

Percentage  by  weight  of  H,,SO4  at  15°.5C. 
(Lung  and  Isler.) 


Specific 
gravity. 

Percentage 
of  H2SO4. 

Specific 
gravity. 

Percentage 
of  H2SO4. 

Specific 
gravity. 

Percentage 
of  H2S04. 

1.005 

0.83 

.200 

27.32 

1.395 

49.59 

1.010 

1.57 

.205 

27.95 

1.400 

50.11 

1.015 

2.30 

.210 

28.58 

1.405 

50.63 

1.020 

3.03 

.215 

29.21 

.410 

51.15 

1.025 

3.76 

.220 

29.84 

.415 

51.66 

1.030 

4.49 

.225 

30.48 

.420 

52.15 

1.035 

5.23 

.230 

31.11 

.425 

52.63 

1.040 

5.96 

.235 

31.70 

.430 

53.11 

1.045 

6.67 

.240 

32.28 

.435 

53.59 

1.050 

7.37 

.245 

32.86 

.440   % 

54.07 

1.055 

8.07 

.250 

33.43 

.445 

54.55 

1.060 

8.77 

.255 

34.00 

.450 

55.03 

1.065 

9.47 

.260 

34.57 

.455 

55.50 

1.070 

10.19 

.265 

35.14 

.460 

55.97 

1.075 

10.90 

.270 

35.71 

.465 

56.43 

1.080 

11.60 

1.275 

36.29 

.470 

56.90 

1.085 

12.30 

1.280 

36.87 

1.475 

57.37 

1.090 

12.99 

1.285 

37.45 

1.480 

57.83 

.095 

13.67 

1.290 

38.03 

1.485 

58.28 

.100 

14.35 

1.295 

:vs  61 

1.490 

58.74 

.105 

15.03 

1.300 

39.19 

1.495 

59.22 

.110 

15.71 

1.305 

39.77 

1.500 

59.70 

.115 

16.36 

.1.310 

40.35 

1.505 

60.18 

.120 

17.01 

1.315 

40.93 

1.510 

60.65 

.125 

17.66 

.320 

41.50 

.515 

61.12 

.130 

18.31 

.325 

42.08 

.520 

61.59 

.135 

18.96 

.330 

42.66 

.525 

62.06 

.140 

19.61 

.335 

43.20 

.530 

62.53 

.145 

20.26 

.340 

43.74 

.535 

63.00 

1.150 

20.91 

.345 

44.28 

.540 

63.43 

1.155 

21.55 

.350 

44.82 

.545 

63.85 

1.160 

22.19 

.355 

45.35 

.550 

64.26 

.165 

22.83 

1.360 

45.88 

.555 

64.67 

.170 

23.47 

1.365 

46.41 

.560 

65.08 

.175 

24.12 

1.370 

46.94 

.565 

65.49 

.180 

24.76 

1.375 

47.47 

.570 

65.90 

.185 

25.40 

1.380 

48.00 

.575 

66.30 

.190 

26.04 

1.385 

48.53 

.580 

66.71 

.195 

26.68 

1.390 

49.06 

.585 

67.13 

328 


THE  LEAD  AND  ZINC  PIGMENTS 


Table  X  (Continued). 


Specific 
gravity. 

Percentage 
of  H2SO4. 

Specific 
gravity. 

Percentage 
of  H2SO4. 

Specific 
gravity. 

Percentage 
of  H2SO4. 

1.590 

67.59 

1.720 

78.92 

.825 

91.00 

.595 

68.05 

1.725 

79.36 

.826 

91.25 

.600 

68.51 

1.730 

79.80 

.827 

91.50 

.605 

68.97 

.735 

80.24 

.828 

91.70 

.610 

69.43 

.740 

80.68 

.829 

91.90 

.615 

69.89 

.745 

81.12 

.830 

92.10 

.620 

70.32 

.750 

81.56 

.831 

92.30 

1.625 

70.74 

.755 

82.00 

.832 

92.52 

1.630 

71.16 

.760 

82.44 

.833 

92.75 

1.635 

71.57 

.765 

82.88 

.834 

93.05 

1.640 

71.99 

.770 

83.32 

.835 

93.43 

1.645 

72.40 

.775 

83.90 

.836 

93.80 

1.650 

72.87 

.780 

84.50 

.837 

94.20 

1.655 

73.23 

.785 

85.10 

.838 

94.60 

1.660 

73.64 

.790 

85.70 

.839 

95.00 

.665 

74.07 

1.795 

86.30 

.840 

95.60 

.670 

74.51 

1.800 

86.90 

.8405 

95.95 

.675 

74.97 

1.805 

87.60 

.8410 

97.00 

.680 

75.42 

.810 

88.30 

.8415 

97.70 

.685 

75.86 

.815 

89.05 

.8410 

98.20 

.690 

76.30 

.820 

90.05 

.8405 

98.70 

.695 

76.73 

.821 

90.20 

.8400 

99.20 

1.700 

77.17 

.822 

90.40 

.8395 

99.45 

1.705 

77.60 

.823 

90.60 

.8390 

99.70 

1.710 

78.04 

.824 

90.80 

.8385 

99.95 

1.715 

78.48 

APPENDIX.  329 


550.   Measures,  Weights  and  Temperatures. 

One  Imperial  gallon  =  277.27  cubic  inches. 

One  wine  gallon  =  231.0  cubic  inches. 

One  wine  gallon  =      3.7854  liters. 

One  wine  gallon  =      8.3389  pounds  water  at  4°  C. 

One  quart  =    57.88  cubic  inches. 

One  quart  .9464  liter. 

One  liter  1.0567  quart. 

One  cubic  foot  =    28,315  cubic  centimeters. 

One  cubic  inch  16.38  cubic  centimeters. 

One  cubic  centimeter  .061  cubic  inch. 

One  pound  Avoirdupois  =  453.6  grams. 

One  ounce  Avoirdupois  =    28.35  grams. 

One  gram  =    15.432  grains. 

One  inch  =        .0254  meter. 

One  foot  =        .3048  meter. 

One  yard  =        .91438  meter. 

One  meter  =    39.3708  inches. 


INDEX. 


A.  PAGE 

Acetic  acid  in  white  lead 264 

conclusions 266 

determination 265 

Action  of  white  lead  on  linseed  oil 138 

Adams  White  Lead  Company 74 

Adulteration  of  white  lead 9 

Ageing  of  white  lead 134 

American  vermilion 222 

care  in  grinding „ 224 

preparation 223 

Amorphous  character  of  white  lead 230 

Analysis  of  commercially  pure  white  leads 258 

metallic  lead 259 

sandy  lead 258 

sulphur  dioxide 258 

tan  bark 259 

Analysis  of  zinc  pigments 268 

calculations 276 

combined  sulphuric  acid 275 

effect 271 

lead 271 

moisture 268 

precipitation  of  zinc  as  carbonate '..:.'....'..  274 

precipitation  of  zinc  as  phosphate !"•    275 

potassium  ferrocyanide  method 272 

reaction  with  rosin  products 270 

silica 268 

standards  of  acceptance 269 

sulphur  dioxide 268 

total  zinc 272 

zinc  sulphate •  •  • ' ." 270 

Annual  production  of  white  lead 35 

Atomic  weights 317 

Average  sample  for  analysis 284 

331 


332  INDEX. 

B.  PAGE 

Bailey  process 27 

Barium  carbonate 297 

Barium  sulphate 296 

Blanc  fixe" 296 

Brands  of  white  lead 34 

C. 

Calcium  carbonate 297 

Carter  process 74 

characteristics  of 84 

chemical  composition  of 82 

granulating  lead 78 

history  of 74 

principles  of 76 

success  of 84 

washing  and  floating 80 

Chalking  of  white  lead 140 

Characteristics  of  English  White  Lead 125 

Chemical  changes  in  grinding 67  and  283 

Chemical  composition  of  white  lead 133 

China  clay 299 

Color  of  white  lead 230 

Combination  leads 71 

Commercial  classification  of  lead  oxides 105 

Comparative  costs  of  manufacture 122 

Comparison  of  pig  lead  and  white  lead  prices 39 

Comparative  prices  of  zinc  oxides 1 79 

D. 

Determination  of  bulking  figure 235 

Determination  of  the  specific  gravity 233 

Development  of  lead  industry  by  the  Dutch 8 

Displacement  of  pigments  in  oil 235 

Dutch  method  of  white  lead  manufacture 11 

E. 

Early  manufacture  of  white  lead  in  United  States 17 

Early  use  of  white  lead 14 

Effect  of  acids  on  white  lead 139 

Effect  of  free  fatty  acids 136 

Effect  of  the  War  of  1812.  .  17 


INDEX  333 

PAGfi 

Effect  of  the  Civil  War 20 

Effect  of  residual  acetates 141 

Effect  of  sulphur  compounds  on  white  lead 139 

English  method  of  grinding 69 

English  method  of  white  lead  manufacture 13  and  123 

English  regulations 122 

Estimation  of  arsenic  and  antimony  at  Cafion  City,  Colorado.  .  . .  279 

Estimation  of  arsenic  and  antimony  in  zinc  leads 276 

Estimation  of  carbon  dioxide 262 

Estimation  of  volatile  oils 311 

Estimation  of  water  in  paints 311 

Extraction  of  vehicle 285 

F. 

Fineness  of  white  lead  particles 136 

Formulas  and  molecular  weights 319 

French  process 1 30 

present  practice .* 131 

G. 

German  chamber  process 125 

corroding 128 

Klagenfurth  modification 125 

.  present  methods 1 27 

rapidity  of  corrosion 1 29 

Gooch  crucible 312 

Gravimetric  factors 320 

Grinding  white  lead 66  and  246 

careless  grinding 246 

conditions  to  be  observed 247 

importance  of  careful  grinding 246 

mixing  and  chasing 247 

Gypsum 298 

H. 

Higher  carbonates  of  lead 134 

I. 

Imports  of  litharge 206 

Improvements  in  Dutch  process 23 

Inaccurate  methods 285 

Independent  white  lead  companies 27 

Inert  pigments 296 


334  INDEX. 


-  PAGE 

Laboratory  equipment  ......................................  310 

Laboratory  tests  for  opacity  and  covering  power  ................  232 

Lead  chromates  ............................................  217 

orange  chrome  yellow  .....................................  221 

practical  formulas  for  ..............  .  ......................  221 

precautions  to  be  observed  ................................  219 

precipitation  of  ..........................................  221 

presence  of  lead  sulphate  in  ................................  218 

raw  materials  for  .........................................  218 

secret  formulas  ...........................................  220 

sodium  bichromate  ........................................  219 

tinting  strength  of  ........................................  217 

use  of  the  calcium  oxide  ...................................  222 

varieties  of  ..............................................  217 

Lead  suboxide  .............................................  200 

Lead  sulphate  .............................................  260 

Leaded  zincs  ..............................................  182 

characteristics  of  .........................................  185 

history  of  ...............................................  182 

process  of  manufacture  ....................................  183 

results  ..................................................  187 

zinc  sulphate  ............................................  187 

Legislation  ............  „  ...................................  148 

Litharge  ........  ...........................................  201 

cupellation  process  ...........  .  ............................  204 

development  of  litharge  industry  ..........................  202 

early  confusion  regarding  nature  of  .........................  202 

manufacture  .............................................  204 

other  processes  ...........................................  204 

properties  ..............................................  205 

Lithopone  .................................................  225 

comparison  with  white  lead  ................................  228 

early  history  .............................................  225 

grades  of  ................................................  228 

manufacturers  of  .........................................  229 

physical  properties  of  .....................................  227 

preparation  of  barium  sulphide  .............................  226 

preparation  of  zinc  sulphate  ...............................  226 

precipitating  and  calcining  ................................  226 

production  of  ............................................  229 

reductions  for  ............................................  227 

zinc  sulphide  ............................................  226 

Location  of  lead  plants  in  United  States  ..........  .  ............  32 


INDEX.  335 

M .  PAGE 

Magnesium  silicate 300 

Manufacture  of  white  lead  in  the  17th  century 9 

Massicot 205 

Matheson  process 101 

characteristics  of  product 103 

development  of 103 

manufacture  by 105 

nature  of 101 

uses  of 107 

Microscopical  measurements 

Mild  process 85 

advantages  of •  •  •  98 

atomizing  the  lead 91 

carbonating •  •  •  93 

control  of 95 

growth  of  process 89 

oxidizing  and  hydrating * 91 

W.  H.  Rowley 

early  training  of 87 

use  of  superheated  steam 87 

Millstones 248 

adjustment  of  grooves 251 

domestic  stones 249 

frequency  of  dressing 255 

grinding  pastes 252 

pneumatic  dressing 254 

proper  selection  of 248 

source  of 248 

speed  of 256. 

stone  dressing 249 

types  of  dressing 256 

use  of  mill  picks 253 

N. 

National  Lead  Trust,  formation  of 23 

absorption  of  other  companies  by.  . 23 

branches  of 25 

dissolution  of 23 

National  Lead  Company,  formation  of 24 

operation  of  factories  by 26 

North  Dakota  paint  tests 238 

conclusions 244 

covering  tests 241 

reductions  used 238 


336  INDEX. 

O.  PAGE 

Obtaining  a  fair  sample 282 

Oil  requirements  and  reductions 231 

Old  Dutch  process 42 

building  the  stack 46 

casting  the  buckles  for 44 

chemical  reactions 50 

conditions  required  for  successful  corrosion 51 

cost  of  production 62 

disintegrating  the  buckles 56 

drying  the  lead 60 

economy  of  process 64 

effect  of  sandy  lead 62 

grade  of  pig  lead  required  for 44 

loss  of  lead  in  washing 60 

sandy  lead 53 

taking  down  the  stack 53 

variation  in  quality 66 

washing  the  lead 56  and  58 

Omaha  White  Lead  Company 74 

Opacity  of  white  lead 231 

Orange  mineral 215 

production  and  imports  of 216 

Oxides  of  lead 200 

classification  of 200 

P. 

Patents  issued 20 

Physical  properties  of  white  lead 230 

Practical  paint  tests 238 

Processes  in  use  in  United  States 42 

Production  of  litharge  in  the  United  States 206 

Production  of  zinc  oxide 181 

Protracted  oxidation 141 

Pulp  ground  lead 71 

characteristics  of 72 

Q. 

Qualitative  analysis  of  combination  leads 295  and  301 

Quantitative  analysis  of  white  leads 302 

alumina 307 

barium  sulphate 307 

calcium  and  magnesium  oxides 307 


INDEX.  337 

PAGE 

Quantitative  analysis  of  white  lead,  calcium 303 

lead  sulphate 306 

magnesium 304 

mixed  carbonates  and  sulphates 308 

silica : 307 

total  lead 302 

white  lead 300 

zinc  oxide 304 


R. 

Rapid  drying 311 

Rapid  extraction  of  pigment 310 

Red  lead 207 

adulteration  of  214 

coloring 211 

development  of  the  industry  * 208 

dressing 211 

early  history  of 207 

early  manufacture  in  the  United  States 208 

early  methods  of  preparation  of 207 

furnace  temperature 209 

modern  improvements 212 

present  methods  of  manufacture 209 

productions  and  imports  of 216 

properties  of 213 

selection  for  vermilions 214 

the  nitrate  process 212 

S. 

Sale  of  dry  white  lead 38 

Short  weight  packages 34 

Silica 300 

Solubility  of  lead  compounds 139 

Specific  gravities 310 

Specific  gravities  corresponding  to  degrees  baume 322  and  323 

Specific  gravity  of  acetic  acid 325 

Specific  gravity  of  hydrochloric  acid 327 

Specific  gravity  of  nitric  acid 326 

Specific  gravity  of  sulphuric  acid 328 

Spiegeleisen 171 

Stability  of  white  lead 139 

Standard  solutions,  bottles  for 312 


338  INDEX. 

PAGE 

Sublimed  blue  lead 120 

composition  of 120 

properties  of 120 

yearly  production 120 

Sublimed  litharge 121 

Sublimed  white  lead 108 

chalking  of 118 

chemical  constitution  of 115 

condensation  of  fume 110 

early  manufacture  of 108 

inertness  of 119 

physical  characteristics  of 117 

sublimation  of  the  ore 110 

uniformity  of  composition 113 

uses  of 118 

whiteness  of 119 

yearly  production 115 

T. 

Table  of  weights  and  measures 330 

U. 

United  Lead  Company,  formation  of 29 

growth  of 29 

Use  of  centrifuge 286 

Use  of  petroleum  thinners 287 

V. 

Variations  from  formula 282 

Volumetric  estimation  of  lead 262 

W. 

Water  in  paints 290 

detection  of 290 

estimation  of 291  and  293 

occurrence  of 290 

Weights  per  gallon 310  and  324 

White  lead  in  ancient  times 1 

White  lead  poisoning 143 

absorption  through  skin 151 

chronic  lead  poisoning 151 

effect  on  nervous  system 150 


INDEX.  339 

PAGE 

White  lead  poisoning,  effect  on  women 149 

English  regulations 144 

English  statistics 146 

precautions 147 

symptoms  of 141) 

White  lead  prices IS 

White  lead  specifications 141 

White  lead,  uses  of 1 

composition  of 1 

early  history  of 2 

early  improvements  in  manufacture  of 6  and  7 

essential  conditions  for  manufacture  of 3 

Whiting 297 


Z. 

Zinc  lead  white 188 

chemical  composition  of i 198 

collection  of  fume 191 

early  manufacture  of 189 

physical  properties  of 194 

production  of 194 

recent  improvements 196 

source  of 188 

s.tandard  of  composition 189 

sublimation  of  fume 191 

use  in  paints 196 

zinc  sulphate 198 

Zinc  oxide  as  a  paint  pigment 179 

Zinc  oxide 162 

analysis  of 176,  177,  178 

collection  of  fume 164 

composition  of  French  oxide 153 

early  history  of 152 

furnace  assays 168 

furnaces 162 

imported  oxides 178 

Mineral  Point  works 171 

New  Jersey  zinc  mines 156 

Palmerton  plant 166 

plants  in  the  United  States 156 

preliminary  treatment  of  ore 160 

present  French  process 153 

processes  in  the  United  States 155 


340  INDEX, 

PAGE 

Zinc  oxide,  properties  of 175 

solubility  in  acids 17«5 

sulphur  dioxide  in 178 

work  of  LeClaire 152 

work  of  Jones  &  Wetherill     155 

zinc  sulphate  in 178 


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Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  00 

Brooks's  Handbook  of  Street  Railroad  Location 16mo,  mor.  1  50 

Butts's  Civil  Engineer's  Field-book 16mo,  mor.  2  50 

Crandall's  Railway  and  Other  Earthwork  Tables 8vo,  1  50 

Transition  Curve 16mo,  mor.  1  50 

*  Crockett's  Methods  for  Earthwork  Computations 8vo.  7   50 

Dredge's  History  of  the  Pennsylvania  Railroad.   (1879) Papet  o  00 

Fisher's  Table  of  Cubic  Yards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide. .  16mo,  mor.  2  50 
Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments  8vo,  1  00 

Ives  and  Hilts's  Problems  in  Surveying,  Railroad  Surveying  and  Geodesy 

16mo,  mor.  1  50 

Molitor  and  Beard's  Manual  for  Resident  Engineers 16mo,  1  00 

Nagle's  Field  Manual  for  Railroad  Engineers 16mo,  mor.  3  00 

*  Orrock's  Railroad  Structures  and  Estimates 8vo,  3  00 

Philbrick's  Field  Manual  for  Engineers 16mo,  mor.  3  00 

Raymond's  Railroad  Engineering.     3  volumes. 

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Vol.    II.  Elements  of  Railroad  Engineering 8vo,  3  50 

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Taylor's  Prismoidal  Formula?  and  Earthwork 8vo,  1  50 

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9 


DRAWING. 

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neers  Oblong  4to,  2  50 

Durley's  Kinematics  of  Machines 8vo,  4  00 

Emch's  Introduction  to  Protective  Geometry  and  its  Application 8vo,  2  50 

French  and  Ives"  Stereotomy 8vo,  2  50 

Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  00 

Jamison's  Advanced  Mechanical  Drawing 8vo,  2  00 

Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design: 

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Kimball  and  Barr's  Machine  Design.      (In  Press.) 

MacCord's  Elements  of  Descritpive  Geometry 8vo,  3  00 

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Reid's  Course  in  Mechanical  Drawing 8vo,  2  00 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design.. 8vo,  3  00 

Robinson's  Principles  of  Mechanism 8vo,  3  00 

Schwamb  and  Merrill's  Elements  of  Mechanism Svo,  3  00 

Smith  (A.  W.)  and  Marx's  Machine  Design 8vo,  3  00 

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Warren's  Drafting  Instruments  and  Operations 12mo,  1  25 

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ments  12mo,  1  00 

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Voltaic  Cell Svo,  3  00 

10 


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Holman's  Precision  of  Measurements 8vo,  2  00 

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Kinzbrunner's  Testing  of  Continuous-current  Machines 8vo,  2  00 

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Reagan's  Locomotives:  Simple,  Compound,  and  Electric.     New  Edition. 

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Schapper's  Laboratory  Guide  for  Students  in  Physical  Chemistry 12mo,  1  00 

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11 


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Emch's  Introduction  to  Projective  Geometry  and  its  Application 8vo,  2  50 

Fiske's  Functions  of  a  Complex  Variable 8vo,  1  00 

Halsted's  Elementary  Synthetic  Geometry 8vo,  1  50 

Elements  of  Geometry 8vo,  1  75 

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Macfarlane's  Vector  Analysis  and  Quaternions 8vo,  1  00 

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Series 12mo,  1  25 

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No.  2.  Synthetic  Projective  Geometry,  by  George  Bruce  Halsted. 
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Maurer's  Technical  Mechanics 8vo,  4  00 

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Variable 8vo.  2  00 

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Weld's  Determinants 8vo,  1  00 

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Woodward's  Probability  and  Theory  of  Errors 8vo,  1  00 

12 


MECHANICAL    ENGINEERING. 

MATERIALS   OF    ENGINEERING,  STEAM-ENGINES   AND    BOILERS. 

Bacon's  Forge  Practice 12mo,  $1  50 

Baldwin's  Steam  Heating  for  Buildings 12mo,  2  50 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  00 

*  "       Abridged  Ed 8vo,  1   50 

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Carpenter's  Experimental  Engineering 8vo,  6  00 

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Clerk's  Gas  and  Oil  Engine.      (New  edition  in  press.) 

Compton's  First  Lessons  in  Metal  Working 12mo,  1  50 

Compton  and  De  Groodt's  Speed  Lathe 12mo,  1  50 

Coolidge's  Manual  of  Drawing 8vo,  paper,  1  00 

Coolidge  and  Freeman's  Elements  of  Geenral  Drafting  for  Mechanical  En- 
gineers  Oblong  4to,  2  50 

Cromwell's  Treatise  on  Belts  and  Pulleys 12mo,  1  50 

Treatise  on  Toothed  Gearing 12mo,  1  50 

Dingey's  Machinery  Pattern  Making 12mo,  2  00 

Durley's  Kinematics  of  Machines 8vo,  4  00 

Flanders's  Gear-cutting  Machinery Large  12mo,  3  00 

Flather's  Dynamometers  and  the  Measurement  of  Power 12mo,  3  00 

Rope  Driving 12mo,  2  00 

Gill's  Gas  and  Fuel  Analysis  for  Engineers 12mo,  1   25 

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Greene's  Pumping  Machinery.      (In  Preparation.) 

Hering's  Ready  Reference  Tables  (Conversion  Factors) 16mo,  mor.  2  50 

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Hutton's  Gas  Engine 8vo,  5  00 

Jamison's  Advanced  Mechanical  Drawing 8vo,  2  00 

Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Gas  Engine 8vo,  4  00 

Machine  Design; 

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Kent's  Mechanical  Engineer's  Pocket-Book 16mo,  mor.  5  00 

Kerr's  Power  and  Power  Transmission 8vo,  2  00 

Kimball  and  Barr's  Machine  Design.      (In  Press.) 

Levin's  Gas  Engine.      (In  Press.) 8vo, 

Leonard's  Machine  Shop  Tools  and  Methods.. 8vo,  4  00 

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MacCord's  Kinematics;  or,  Practical  Mechanism 8vo,  5  00 

Mechanical  Drawing 4to,  4  00 

Velocity  Diagrams 8vo,  1  50 

MacFarland's  Standard  Reduction  Factors  for  Gases 8vo,  1  50 

Mahan's  Industrial  Drawing.      (Thompson.) 8vo,  3  50 

Mehrtens's  Gas  Engine  Theory  and  Design Large  12mo,  2  50 

Oberg's  Handbook  of  Small  Tools Large  12mo.  3  00 

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*  Porter's  Engineering  Reminiscences,  1855  to  1882 8vo,  3  00 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  00 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design.Svo,  3  00 

Richards's  Compressed  Air 12mo,  1  50 

Robinson's  Principles  of  Mechanism.  .  .  . 8vo,  3  00 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  00 

Smith  (A.  W.)  and  Marx's  Machine  Design 8vo,  3  00 

Smith's  (O.)  Press- working  of  Metals 8vo,  3  00 

Sorel's  Carbureting  and  Combustion  in  Alcohol  Engines.      (Woodward  and 

Preston.) Large  12mo,  3  00 

Stone's  Practical  Testing  of  Gas  and  Gas  Meters 8vo,  3  50 

13 


Thurston's  Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics. 

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Treatise  on  Friction  and  Lost  Work  in  Machinery  and  Mill  Work.  .  .8vo,  3  00 

*  Tillson's  Complete  Automobile  Instructor 16mo,  1  50 

*  Titsworth's  Elements  of  Mechanical  Drawing Oblong  8vo,  1  25 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

*  Waterbury's  Vest  Pocket  Hand-book  of  Mathematics  for  Engineers. 

21  X  5f  inches,  mor.  1  00 
Weisbach's    Kinematics    and    the    Power   of    Transmission.      (Herrmann — 

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Wood's  Turbines 8vo,  2  50 


MATERIALS    OF   ENGINEERING. 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Church's  Mechanics  of  Engineering 8vo,  6  00 

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Johnson's  (C.  M.)  Rapid    Methods    for    the    Chemical    Analysis    of    Special 

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Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Maire's  Modern  Pigments  and  their  Vehicles 12mo,  2  00 

Martens's  Handbook  on  Testing  Materials.      (Henning.) 8vo,  7  50 

Maurer's  Technical  Mechanics 8vo,  4  00 

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Thurston's  Materials  of  Engineering 3  vols.,  8vo,  8  00 

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Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,  3  00 

Treatise  on    the    Resistance    of    Materials    and    an    Appendix    on    the 

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Wood's  (M.  P.)   Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

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Hemen way's  Indicator  Practice  and  Steam-engine  Economy 12mo,  2  00 

Button's  Heat  and  Heat-engines 8vo,  5  00 

Mechanical  Engineering  of  Power  Plants 8vo,  5  00 

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14 


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Pupin's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. 

(Osterberg.) , 12mo.  1  25 

Reagan's  Locomotives:  Simple,  Compound,  and  Electric.     New  Edition. 

Large  12mo,  3  50 

Sinclair's  Locomotive  Engine  Running  and  Management 12mo,  2  00 

Smart's  Handbook  of  Engineering  Laboratory  Practice 12mo,  2  50 

Snow's  Steam-boiler  Practice 8vo,  3  00 

Spangler's  Notes  on  Thermodynamics 12mo.  1  00 

Valve-gears 8vo,  2  50 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  00 

Thomas's  Steam-turbines 8vo,  4  00 

Thurston's  Handbook  of  Engine  and  Boiler  Trials,  ami  the  Use  of  the  Indi- 
cator and  the  Prony  Brake 8vo,  5  00 

Handy  Tables 8vo,  1  50 

Manual  of  Steam-boilers,  their  Designs,  Construction,  and  Operation  8vo,  5  00 

Manual  of  the  Steam-engine 2vols.,  8vo.  10  00 

Part  I.      History,  Structure,  and  Theory 8vo.  6  00 

Part  II.      Design,  Construction,  and  Operation 8vo,  6  00 

Steam-boiler  Explosions  in  Theory  and  in  Practice 12mo,  1  50 

Wehrenfennig's    Analysis  and  Softening  of  Boiler  Feed-water.     (Patterson). 

8vo,  4  00 

Weisbach's  Heat,  Steam,  and  Steam-engines.      (Du  Bois.) 8vo,  5  00 

Whitham's  Steam-engine  Design 8vo,  5  00 

Wood's  Thermodynamics,  Heat  Motors,  and  Refrigerating  Machines.  .  .8vo,  4  00 


MECHANICS    PURE   AND    APPLIED. 

Church's  Mechanics  of  Engineering 8vo,  6  00 

Notes  and  Examples  in  Mechanics 8vo,  2  00 

Dana's  Text-book  of  Elementary  Mechanics  for  Colleges  and  Schools  .12mo,  1  50 
Du  Bois's  Elementary  Principles  of  Mechanics: 

Vol.    I.     Kinematics 8vo,  3  50 

Vol.  II.     Statics 8vo,  4  00 

Mechanics  of  Engineering.     Vol.     I Small  4to,  7  50 

Vol.  II Small  4to,  10  00 

*  Greene's  Structural  Mechanics 8vo,  2  50 

James's  Kinematics  of  a  Point  and  the  Rational  Mechanics  of  a  Particle. 

Large  12mo,  2  00 

*  Johnson's  (W.  W.)  Theoretical  Mechanics 12mo,  3  00 

Lanza's  Applied  Mechanics 8vo,  7  50 

*  Martin's  Text  Book  on  Mechanics.  Vol.  I,  Statics 12mo,  1  25 

*  Vol.  II,  Kinematics  and  Kinetics.  12mo,  1  50 

Maurer's  Technical  Mechanics 8vo,  4  00 

*  Merriman's  Elements  of  Mechanics 12mo,  1   00 

Mechanics  of  Materials 8vo,  5  00 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  00 

Robinson's  Principles  of  Mechanism 8vo,  3  00 

Sanborn's  Mechanics  Problems Large  12mo,  1  50 

Schwamb  and  Merrill's  Elements  of  Mechanism .8vo,  3  00 

Wood's  Elements  of  Analytical  Mechanics 8vo,  3  00 

Principles  of  Elementary  Mechanics 12mo,  1  25 


15 


MEDICAL. 

*  Abderhalden's  Physiological   Chemistry   in   Thirty   Lectures.     (Hall   and 

Defren.) 8vo,  $5  00 

von  Behring's  Suppression  of  Tuberculosis.      (Bolduan.) 12mo,  1  00 

Bolduan's  Immune  Sera 12mo,  1  50 

Bordet's  Studies  in  Immunity.      (Gay).      (In  Press.) 8vo, 

Davenport's  Statistical  Methods  with  Special  Reference  to  Biological  Varia- 
tions  16mo,  mor.  1  50 

Ehrlich's  Collected  Studies  on  Immunity.      (Bolduan.) 8vo,  6  00 

*  Fischer's  Physiology  of  Alimentation Large  12mo,  2  09 

de  Fursac's  Manual  of  Psychiatry.      (Rosanoff  and  Collins.)..  .  .Large  12mo,  2  50 

Hammarsten's  Text-book  on  Physiological  Chemistry.      (Mandel.) 8vo,  4  00 


Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo, 

Lassar-Cohn's  Practical  Urinary  Analysis.      (Lorenz.) 12mo, 

Mandel's  Hand-book  for  the  Bio-Chemical  Laboratory 12mo, 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.      (Fischer.)  ..12mo, 


*  Pozzi-Escot's  Toxins  and  Venoms  and  their  Antibodies.      (Cohn.).  .  12mo, 

Rostoski's  Serum  Diagnosis.      (Bolduan.) 12mo, 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo,  2  00 

Whys  in  Pharmacy 12mo,  1  00 

Salkowski's  Physiological  and  Pathological  Chemistry.      (Orndorff.)  ....8vo,  250 

*  Satterlee's  Outlines  of  Human  Embryology 12mo,  1  25 

Smith's  Lecture  Notes  on  Chemistry  for  Dental  Students 8vo,  2  50 

*  Whipple's  Tyhpoid  Fever Large  12mo,  3  00 

Woodhull's  Notes  on  Military  Hygiene 16mo,  1  50 

*  Personal  Hygiene 12mo,  1  00 

Worcester  and  Atkinson's  Small  Hospitals  Establishment  and  Maintenance, 
and  Suggestions  for  Hospital  Architecture,  with  Plans  for  a  Small 

Hospital 12mo,  1  25 


METALLURGY. 

Betts's  Lead  Refining  by  Electrolysis 8vo,  4  00 

Bolland's  Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  used 

in  the  Practice  of  Moulding 12mo,  3  00 

Iron  Founder 12mo,  2  50 

Supplement 12mo,  2  50 

Douglas's  Untechnical  Addresses  on  Technical  Subjects 12mo,  1  00 

Goesel's  Minerals  and  Metals:  A  Reference  Book 16mo,  mor.  3  00 

*  Iles's  Lead-smelting 12mo,  2  50 

Johnson's    Rapid    Methods   for    the   Chemical   Analysis   of   Special   Steels, 

Steel-making  Alloys  and  Graphite Large  12mo,  3  00 

Keep's  Cast  Iron 8vo,  2  50 

Le  Chatelier's  High- temperature  Measurements.     (Boudouard — Burgess.) 

12mo,  3  00 

Metcalf's  Steel.      A  Manual  for  Steel-users 12mo,  2  00 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.      (Waldo.).  .  12mo,  2  50 

Ruer's  Elements  of  Metallography.      (Mathewson) 8vo, 

Smith's  Materials  of  Machines 12mo,  1  00 

Tate  and  Stone's  Foundry  Practice 12mo,  2  00 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo,  8  00 

Part  I.       Non-metallic  Materials  of  Engineering,  see  Civil  Engineering, 
page  9. 

Part  II.     Iron  and  Steel 8vo,  3  50 

Part  III.  A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  00 

West's  American  Foundry  Practice 12mo,  2  50 

Moulders'  Text  Book 12mo,  2  50 

16 


MINERALOGY. 

Baskerville's  Chemical  Elements.     (In  Preparation.). 

Boyd's  Map  of  Southwest  Virginia Pocket-book  form.  $2  00 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  1  50 

Brush's  Manual  of  Determinative  Mineralogy.      (Penfield.) 8vo,  4  00 

Butler's  Pocket  Hand-book  of  Minerals 16mo,  mor.  3  00 

Chester's  Catalogue  of  Minerals 8vo,  paper,     1  00 

Cloth,  1   25 

*  Crane's  Gold  and  Silver 8vo,  5  00 

Dana's  First  Appendix  to  Dana's  New  "System  of  Mineralogy".  .Large  8vo,  1  00 
Dana's  Second  Appendix  to  Dana's  New  "System  of  Mineralogy." 

Large  8vo, 

Manual  of  Mineralogy  and  Petrography 12mo,  2  00 

Minerals  and  How  to  Study  Them 12mo.  1  50 

System  of  Mineralogy Large  8vo,  half  leather,  12  50 

Text-book  of  Mineralogy 8vo,  4  00 

Douglas's  Untechnical  Addresses  on  Technical  Subjects 12mo,  1  00 

Eakle's  Mineral  Tables 8vo.  1  25 

Eckel's  Stone  and  Clay  Products  Used  in  Engineering.     (In  Preparation). 

Goesel's  Minerals  and  Metals:  A  Reference  Book 16mo,  mor.  3  00 

Groth's  Introduction  to  Chemical  Crystallography  (Marshall) 12mo.  1   25 

*  Hayes's  Handbook  for  Field  Geologists 16mo,  mor.  1   50 

Iddings's  Igneous  Rocks 8vo,  5  00 

Rock  Minerals 8vo.  5  00 

Johannsen's  Determination  of  Rock  forming  Minerals  in  Thin  Sections.  8vo. 

With  Thumb  Index  5  00 

*  Martin's  Laboratory    Guide    to    Qualitative    Analysis    with    the    Blow- 

pipe  12mo,  60 

Merrill's  Non-metallic  Minerals.  Their  Occurrence  and  Uses 8vo.  4  00 

Stones  for  Building  and  Decoration 8vo.  5  00 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo.  paper.  50 
Tables  of  Minerals,   Including  the  Use  of   Minerals  and  Statistics  of 

Domestic  Production 8vo.  1  00 

*  Pirsson's  Rocks  and  Rock  Minerals 12mo,  2  50 

*  Richards's  Synopsis  of  Mineral  Characters 12mo,  mor.  1  25 

*  Ries's  Clays :  Their  Occurrence,  Properties  and  Uses 8vo.  5  00 

*  Ries  and  Leighton's  History  of  the  Clay-working  Industry  of  the  United 

States 8vo.  2  50 

*  Tillman's  Text-book  of  Important  Minerals  and  Rocks 8voT  2  06 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8vo,  2  00 


MINING. 

*  Beard's  Mine  Gases  and  Explosions Large  12mo,  3  00 

Boyd's  Map  of  Southwest  Virginia Pocket-book  form,  2  00 

*  Crane's  Gold  and  Silver 8vo.  5  00 

*  Index  of  Mining  Engineering  Literature 8vo.  4  00 

*  8vo.  mor.  5  00 

Douglas's  Untechnical  Addresses  on  Technical  Subjects 12mo.  1  00 

Eissler's  Modern  High  Explosives 8vo.  4  00 

Goesel's  Minerals  and  Metals:  A  Reference  Book 16mo.  mor.  3  00 

Ihlseng's  Manual  of  Mining 8vo,  5  00 

*  Iles's  Lead  Smelting 12mo.  2  50 

Peele's  Compressed  Air  Plant  for  Mines 8vo.  3  00 

Riemer's  Shaft  Sinking  Under  Difficult  Conditions.     (Corning  and  Peele).8vo,  3  00 

*  Weaver's  Military  Explosives gVOi  3  QQ 

Wilson's  Hydraulic  and  Placer  Mining.     2d  edition   rewritten 12mo,  2  50 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation 12mo.  1  25 

17 


SANITARY   SCIENCE. 

Association  of  State  and  National  Food  and  Dairy  Departments,  Hartford 

Meeting,  1906 8vo,  $3  00 

Jamestown  Meeting,  1907 8vo,  3  00 

*  Bashore's  Outlines  of  Practical  Sanitation 12mo,  1  25 

Sanitation  of  a  Country  House 12mo,  1  00 

Sanitation  of  Recreation  Camps  and  Parks 12mo,  1  00 

Folwell's  Sewerage.      (Designing,  Construction,  and  Maintenance.) 8vo,  3  00 

Water-supply  Engineering 8vo,  4  00 

Fowler's  Sewage  Works  Analyses 12mo,  2  00 

Fuertes's  Water-filtration  Works 12mo,  2  50 

Water  and  Public  Health '. 12mo,  1  50 

Gerhard's  Guide  to  Sanitary  Inspections 12mo,  1  50 

*  Modern  Baths  and  Bath  Houses 8vo,  3  00 

Sanitation  of  Public  Buildings 12mo,  1  50 

Hazen's  Clean  Water  and  How  to  Get  It Large  12mo,  1  50 

Filtration  of  Public  Water-supplies 8vo,  3  00 

Kinnicut,  Winslow  and  Pratt's  Purification  of  Sewage.      (In  Preparation.) 
Leach's  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,  7  50 

Mason's  Examination  of  Water.      (Chemical  and  Bacteriological) 12mo,  1  25 

Water-supply.      (Considered  principally  from  a  Sanitary  Standpoint). 

8vo,  4  00 

*  Merriman's  Elements  of  Sanitary  Enigneering 8vo,  2  00 

Ogden's  Sewer  Construction 8vo,  3  00 

Sewer  Design 12mo,  2  00 

Parsons's  Disposal  of  Municipal  Refuse 8vo,  2  00 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis 12mo,  1  50 

*  Price's  Handbook  on  Sanitation 12mo,  1  50 

Richards's  Cost  of  Cleanness 12mo,  1  00 

Cost  of  Food.      A  Study  in  Dietaries 12mo,  1  00 

Cost  of  Living  as  Modified  by  Sanitary  Science 12mo,  1  00 

Cost  of  Shelter 12mo,  1  00 

*  Richards  and  Williams's  Dietary  Computer 8vo,  1  50 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Stand- 
point  8vo,  2  00 

*  Richey's     Plumbers',     Steam-fitters',    and     Tinners'     Edition     (Building 

Mechanics'  Ready  Reference  Series) 16mo,  mor.  1  50 

Rideal's  Disinfection  and  the  Preservation  of  Food 8vo,  4  00 

Sewage  and  Bacterial  Purification  of  Sewage 8vo,  4  00 

Soper's  Air  and  Ventilation  of  Subways 12mo,  2  50 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  00 

Venable's  Garbage  Crematories  in  America 8vo,  2  00 

Method  and  Devices  for  Bacterial  Treatment  of  Sewage 8vo,  3  00 

Ward  and  Whipple's  Freshwater  Biology.      (In  Press.) 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

*  Typhoid  Fever Large  12mo,  3  00 

Value  of  Pure  Water Large  12mo,  1  00 

Winslow's  Systematic  Relationship  of  the  Coccaceas Large  12mo,  2  50 


MISCELLANEOUS. 

Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  8vo.  1  50 

Ferrel's  Popular  Treatise  on  the  Winds 8vo,  4  00 

Fitzgerald's  Boston  Machinist 18mo,  1  00 

Gannett's  Statistical  Abstract  of  the  World 24mo,  75 

Haines's  American  Railway  Management 12mo,  2  50 

Hanausek's  The  Microscopy  of  Technical  Products.     (Winton) 8vo,  5  00 

18 


Jacobs's  Betterment    Briefs.     A    Collection    of    Published    Papers    on    Or- 
ganized Industrial  Efficiency 8vo,  $3   50 

Metcalfe's  Cost  of  Manufactures,  and  the  Administration  of  Workshops.. 8vo,  5  00 

Putnam's  Nautical  Charts 8vo,  2  OO 

Ricketts's  History  of  Rensselaer  Polytechnic  Institute  1824-1894. 

Large  12mo,  3  oo 

Rotherham's  Emphasised  New  Testament Large  8vo,  2  OO 

Rust's  Ex-Meridian  Altitude,  Azimuth  and  Star-finding  Tables 8vo,  5  00 

Standage's  Decoration  of  Wood,  Glass,  Metal,  etc 12mo,  2  00 

Thome's  Structural  and  Physiological  Botany.      (Bennett) 16mo,  2  25 

Westermaier's  Compendium  of  General  Botany.     (Schneider) 8vo.  2  00 

Winslow's  Elements  of  Applied  Microscopy 12mo,  1  50 


HEBREW    AND    CHALDEE    TEXT-BOOOKS. 

Gesenius's  Hebrew  and  Chaldee  Lexicon  to  the  Old  Testament  Scriptures. 

(Tregelles.) Small  4to,  half  mor.     5  00 

Green's  Elementary  Hebrew  Grammar 12mo,      1   25 


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